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Edit File: cgi.py
#! /usr/bin/python3.9 # NOTE: the above "/usr/local/bin/python" is NOT a mistake. It is # intentionally NOT "/usr/bin/env python". On many systems # (e.g. Solaris), /usr/local/bin is not in $PATH as passed to CGI # scripts, and /usr/local/bin is the default directory where Python is # installed, so /usr/bin/env would be unable to find python. Granted, # binary installations by Linux vendors often install Python in # /usr/bin. So let those vendors patch cgi.py to match their choice # of installation. """Support module for CGI (Common Gateway Interface) scripts. This module defines a number of utilities for use by CGI scripts written in Python. """ # History # ------- # # Michael McLay started this module. Steve Majewski changed the # interface to SvFormContentDict and FormContentDict. The multipart # parsing was inspired by code submitted by Andreas Paepcke. Guido van # Rossum rewrote, reformatted and documented the module and is currently # responsible for its maintenance. # __version__ = "2.6" # Imports # ======= from io import StringIO, BytesIO, TextIOWrapper from collections.abc import Mapping import sys import os import urllib.parse from email.parser import FeedParser from email.message import Message import html import locale import tempfile __all__ = ["MiniFieldStorage", "FieldStorage", "parse", "parse_multipart", "parse_header", "test", "print_exception", "print_environ", "print_form", "print_directory", "print_arguments", "print_environ_usage"] # Logging support # =============== logfile = "" # Filename to log to, if not empty logfp = None # File object to log to, if not None def initlog(*allargs): """Write a log message, if there is a log file. Even though this function is called initlog(), you should always use log(); log is a variable that is set either to initlog (initially), to dolog (once the log file has been opened), or to nolog (when logging is disabled). The first argument is a format string; the remaining arguments (if any) are arguments to the % operator, so e.g. log("%s: %s", "a", "b") will write "a: b" to the log file, followed by a newline. If the global logfp is not None, it should be a file object to which log data is written. If the global logfp is None, the global logfile may be a string giving a filename to open, in append mode. This file should be world writable!!! If the file can't be opened, logging is silently disabled (since there is no safe place where we could send an error message). """ global log, logfile, logfp if logfile and not logfp: try: logfp = open(logfile, "a") except OSError: pass if not logfp: log = nolog else: log = dolog log(*allargs) def dolog(fmt, *args): """Write a log message to the log file. See initlog() for docs.""" logfp.write(fmt%args + "\n") def nolog(*allargs): """Dummy function, assigned to log when logging is disabled.""" pass def closelog(): """Close the log file.""" global log, logfile, logfp logfile = '' if logfp: logfp.close() logfp = None log = initlog log = initlog # The current logging function # Parsing functions # ================= # Maximum input we will accept when REQUEST_METHOD is POST # 0 ==> unlimited input maxlen = 0 def parse(fp=None, environ=os.environ, keep_blank_values=0, strict_parsing=0, separator='&'): """Parse a query in the environment or from a file (default stdin) Arguments, all optional: fp : file pointer; default: sys.stdin.buffer environ : environment dictionary; default: os.environ keep_blank_values: flag indicating whether blank values in percent-encoded forms should be treated as blank strings. A true value indicates that blanks should be retained as blank strings. The default false value indicates that blank values are to be ignored and treated as if they were not included. strict_parsing: flag indicating what to do with parsing errors. If false (the default), errors are silently ignored. If true, errors raise a ValueError exception. separator: str. The symbol to use for separating the query arguments. Defaults to &. """ if fp is None: fp = sys.stdin # field keys and values (except for files) are returned as strings # an encoding is required to decode the bytes read from self.fp if hasattr(fp,'encoding'): encoding = fp.encoding else: encoding = 'latin-1' # fp.read() must return bytes if isinstance(fp, TextIOWrapper): fp = fp.buffer if not 'REQUEST_METHOD' in environ: environ['REQUEST_METHOD'] = 'GET' # For testing stand-alone if environ['REQUEST_METHOD'] == 'POST': ctype, pdict = parse_header(environ['CONTENT_TYPE']) if ctype == 'multipart/form-data': return parse_multipart(fp, pdict, separator=separator) elif ctype == 'application/x-www-form-urlencoded': clength = int(environ['CONTENT_LENGTH']) if maxlen and clength > maxlen: raise ValueError('Maximum content length exceeded') qs = fp.read(clength).decode(encoding) else: qs = '' # Unknown content-type if 'QUERY_STRING' in environ: if qs: qs = qs + '&' qs = qs + environ['QUERY_STRING'] elif sys.argv[1:]: if qs: qs = qs + '&' qs = qs + sys.argv[1] environ['QUERY_STRING'] = qs # XXX Shouldn't, really elif 'QUERY_STRING' in environ: qs = environ['QUERY_STRING'] else: if sys.argv[1:]: qs = sys.argv[1] else: qs = "" environ['QUERY_STRING'] = qs # XXX Shouldn't, really return urllib.parse.parse_qs(qs, keep_blank_values, strict_parsing, encoding=encoding, separator=separator) def parse_multipart(fp, pdict, encoding="utf-8", errors="replace", separator='&'): """Parse multipart input. Arguments: fp : input file pdict: dictionary containing other parameters of content-type header encoding, errors: request encoding and error handler, passed to FieldStorage Returns a dictionary just like parse_qs(): keys are the field names, each value is a list of values for that field. For non-file fields, the value is a list of strings. """ # RFC 2026, Section 5.1 : The "multipart" boundary delimiters are always # represented as 7bit US-ASCII. boundary = pdict['boundary'].decode('ascii') ctype = "multipart/form-data; boundary={}".format(boundary) headers = Message() headers.set_type(ctype) try: headers['Content-Length'] = pdict['CONTENT-LENGTH'] except KeyError: pass fs = FieldStorage(fp, headers=headers, encoding=encoding, errors=errors, environ={'REQUEST_METHOD': 'POST'}, separator=separator) return {k: fs.getlist(k) for k in fs} def _parseparam(s): while s[:1] == ';': s = s[1:] end = s.find(';') while end > 0 and (s.count('"', 0, end) - s.count('\\"', 0, end)) % 2: end = s.find(';', end + 1) if end < 0: end = len(s) f = s[:end] yield f.strip() s = s[end:] def parse_header(line): """Parse a Content-type like header. Return the main content-type and a dictionary of options. """ parts = _parseparam(';' + line) key = parts.__next__() pdict = {} for p in parts: i = p.find('=') if i >= 0: name = p[:i].strip().lower() value = p[i+1:].strip() if len(value) >= 2 and value[0] == value[-1] == '"': value = value[1:-1] value = value.replace('\\\\', '\\').replace('\\"', '"') pdict[name] = value return key, pdict # Classes for field storage # ========================= class MiniFieldStorage: """Like FieldStorage, for use when no file uploads are possible.""" # Dummy attributes filename = None list = None type = None file = None type_options = {} disposition = None disposition_options = {} headers = {} def __init__(self, name, value): """Constructor from field name and value.""" self.name = name self.value = value # self.file = StringIO(value) def __repr__(self): """Return printable representation.""" return "MiniFieldStorage(%r, %r)" % (self.name, self.value) class FieldStorage: """Store a sequence of fields, reading multipart/form-data. This class provides naming, typing, files stored on disk, and more. At the top level, it is accessible like a dictionary, whose keys are the field names. (Note: None can occur as a field name.) The items are either a Python list (if there's multiple values) or another FieldStorage or MiniFieldStorage object. If it's a single object, it has the following attributes: name: the field name, if specified; otherwise None filename: the filename, if specified; otherwise None; this is the client side filename, *not* the file name on which it is stored (that's a temporary file you don't deal with) value: the value as a *string*; for file uploads, this transparently reads the file every time you request the value and returns *bytes* file: the file(-like) object from which you can read the data *as bytes* ; None if the data is stored a simple string type: the content-type, or None if not specified type_options: dictionary of options specified on the content-type line disposition: content-disposition, or None if not specified disposition_options: dictionary of corresponding options headers: a dictionary(-like) object (sometimes email.message.Message or a subclass thereof) containing *all* headers The class is subclassable, mostly for the purpose of overriding the make_file() method, which is called internally to come up with a file open for reading and writing. This makes it possible to override the default choice of storing all files in a temporary directory and unlinking them as soon as they have been opened. """ def __init__(self, fp=None, headers=None, outerboundary=b'', environ=os.environ, keep_blank_values=0, strict_parsing=0, limit=None, encoding='utf-8', errors='replace', max_num_fields=None, separator='&'): """Constructor. Read multipart/* until last part. Arguments, all optional: fp : file pointer; default: sys.stdin.buffer (not used when the request method is GET) Can be : 1. a TextIOWrapper object 2. an object whose read() and readline() methods return bytes headers : header dictionary-like object; default: taken from environ as per CGI spec outerboundary : terminating multipart boundary (for internal use only) environ : environment dictionary; default: os.environ keep_blank_values: flag indicating whether blank values in percent-encoded forms should be treated as blank strings. A true value indicates that blanks should be retained as blank strings. The default false value indicates that blank values are to be ignored and treated as if they were not included. strict_parsing: flag indicating what to do with parsing errors. If false (the default), errors are silently ignored. If true, errors raise a ValueError exception. limit : used internally to read parts of multipart/form-data forms, to exit from the reading loop when reached. It is the difference between the form content-length and the number of bytes already read encoding, errors : the encoding and error handler used to decode the binary stream to strings. Must be the same as the charset defined for the page sending the form (content-type : meta http-equiv or header) max_num_fields: int. If set, then __init__ throws a ValueError if there are more than n fields read by parse_qsl(). """ method = 'GET' self.keep_blank_values = keep_blank_values self.strict_parsing = strict_parsing self.max_num_fields = max_num_fields self.separator = separator if 'REQUEST_METHOD' in environ: method = environ['REQUEST_METHOD'].upper() self.qs_on_post = None if method == 'GET' or method == 'HEAD': if 'QUERY_STRING' in environ: qs = environ['QUERY_STRING'] elif sys.argv[1:]: qs = sys.argv[1] else: qs = "" qs = qs.encode(locale.getpreferredencoding(), 'surrogateescape') fp = BytesIO(qs) if headers is None: headers = {'content-type': "application/x-www-form-urlencoded"} if headers is None: headers = {} if method == 'POST': # Set default content-type for POST to what's traditional headers['content-type'] = "application/x-www-form-urlencoded" if 'CONTENT_TYPE' in environ: headers['content-type'] = environ['CONTENT_TYPE'] if 'QUERY_STRING' in environ: self.qs_on_post = environ['QUERY_STRING'] if 'CONTENT_LENGTH' in environ: headers['content-length'] = environ['CONTENT_LENGTH'] else: if not (isinstance(headers, (Mapping, Message))): raise TypeError("headers must be mapping or an instance of " "email.message.Message") self.headers = headers if fp is None: self.fp = sys.stdin.buffer # self.fp.read() must return bytes elif isinstance(fp, TextIOWrapper): self.fp = fp.buffer else: if not (hasattr(fp, 'read') and hasattr(fp, 'readline')): raise TypeError("fp must be file pointer") self.fp = fp self.encoding = encoding self.errors = errors if not isinstance(outerboundary, bytes): raise TypeError('outerboundary must be bytes, not %s' % type(outerboundary).__name__) self.outerboundary = outerboundary self.bytes_read = 0 self.limit = limit # Process content-disposition header cdisp, pdict = "", {} if 'content-disposition' in self.headers: cdisp, pdict = parse_header(self.headers['content-disposition']) self.disposition = cdisp self.disposition_options = pdict self.name = None if 'name' in pdict: self.name = pdict['name'] self.filename = None if 'filename' in pdict: self.filename = pdict['filename'] self._binary_file = self.filename is not None # Process content-type header # # Honor any existing content-type header. But if there is no # content-type header, use some sensible defaults. Assume # outerboundary is "" at the outer level, but something non-false # inside a multi-part. The default for an inner part is text/plain, # but for an outer part it should be urlencoded. This should catch # bogus clients which erroneously forget to include a content-type # header. # # See below for what we do if there does exist a content-type header, # but it happens to be something we don't understand. if 'content-type' in self.headers: ctype, pdict = parse_header(self.headers['content-type']) elif self.outerboundary or method != 'POST': ctype, pdict = "text/plain", {} else: ctype, pdict = 'application/x-www-form-urlencoded', {} self.type = ctype self.type_options = pdict if 'boundary' in pdict: self.innerboundary = pdict['boundary'].encode(self.encoding, self.errors) else: self.innerboundary = b"" clen = -1 if 'content-length' in self.headers: try: clen = int(self.headers['content-length']) except ValueError: pass if maxlen and clen > maxlen: raise ValueError('Maximum content length exceeded') self.length = clen if self.limit is None and clen >= 0: self.limit = clen self.list = self.file = None self.done = 0 if ctype == 'application/x-www-form-urlencoded': self.read_urlencoded() elif ctype[:10] == 'multipart/': self.read_multi(environ, keep_blank_values, strict_parsing) else: self.read_single() def __del__(self): try: self.file.close() except AttributeError: pass def __enter__(self): return self def __exit__(self, *args): self.file.close() def __repr__(self): """Return a printable representation.""" return "FieldStorage(%r, %r, %r)" % ( self.name, self.filename, self.value) def __iter__(self): return iter(self.keys()) def __getattr__(self, name): if name != 'value': raise AttributeError(name) if self.file: self.file.seek(0) value = self.file.read() self.file.seek(0) elif self.list is not None: value = self.list else: value = None return value def __getitem__(self, key): """Dictionary style indexing.""" if self.list is None: raise TypeError("not indexable") found = [] for item in self.list: if item.name == key: found.append(item) if not found: raise KeyError(key) if len(found) == 1: return found[0] else: return found def getvalue(self, key, default=None): """Dictionary style get() method, including 'value' lookup.""" if key in self: value = self[key] if isinstance(value, list): return [x.value for x in value] else: return value.value else: return default def getfirst(self, key, default=None): """ Return the first value received.""" if key in self: value = self[key] if isinstance(value, list): return value[0].value else: return value.value else: return default def getlist(self, key): """ Return list of received values.""" if key in self: value = self[key] if isinstance(value, list): return [x.value for x in value] else: return [value.value] else: return [] def keys(self): """Dictionary style keys() method.""" if self.list is None: raise TypeError("not indexable") return list(set(item.name for item in self.list)) def __contains__(self, key): """Dictionary style __contains__ method.""" if self.list is None: raise TypeError("not indexable") return any(item.name == key for item in self.list) def __len__(self): """Dictionary style len(x) support.""" return len(self.keys()) def __bool__(self): if self.list is None: raise TypeError("Cannot be converted to bool.") return bool(self.list) def read_urlencoded(self): """Internal: read data in query string format.""" qs = self.fp.read(self.length) if not isinstance(qs, bytes): raise ValueError("%s should return bytes, got %s" \ % (self.fp, type(qs).__name__)) qs = qs.decode(self.encoding, self.errors) if self.qs_on_post: qs += '&' + self.qs_on_post query = urllib.parse.parse_qsl( qs, self.keep_blank_values, self.strict_parsing, encoding=self.encoding, errors=self.errors, max_num_fields=self.max_num_fields, separator=self.separator) self.list = [MiniFieldStorage(key, value) for key, value in query] self.skip_lines() FieldStorageClass = None def read_multi(self, environ, keep_blank_values, strict_parsing): """Internal: read a part that is itself multipart.""" ib = self.innerboundary if not valid_boundary(ib): raise ValueError('Invalid boundary in multipart form: %r' % (ib,)) self.list = [] if self.qs_on_post: query = urllib.parse.parse_qsl( self.qs_on_post, self.keep_blank_values, self.strict_parsing, encoding=self.encoding, errors=self.errors, max_num_fields=self.max_num_fields, separator=self.separator) self.list.extend(MiniFieldStorage(key, value) for key, value in query) klass = self.FieldStorageClass or self.__class__ first_line = self.fp.readline() # bytes if not isinstance(first_line, bytes): raise ValueError("%s should return bytes, got %s" \ % (self.fp, type(first_line).__name__)) self.bytes_read += len(first_line) # Ensure that we consume the file until we've hit our inner boundary while (first_line.strip() != (b"--" + self.innerboundary) and first_line): first_line = self.fp.readline() self.bytes_read += len(first_line) # Propagate max_num_fields into the sub class appropriately max_num_fields = self.max_num_fields if max_num_fields is not None: max_num_fields -= len(self.list) while True: parser = FeedParser() hdr_text = b"" while True: data = self.fp.readline() hdr_text += data if not data.strip(): break if not hdr_text: break # parser takes strings, not bytes self.bytes_read += len(hdr_text) parser.feed(hdr_text.decode(self.encoding, self.errors)) headers = parser.close() # Some clients add Content-Length for part headers, ignore them if 'content-length' in headers: del headers['content-length'] limit = None if self.limit is None \ else self.limit - self.bytes_read part = klass(self.fp, headers, ib, environ, keep_blank_values, strict_parsing, limit, self.encoding, self.errors, max_num_fields, self.separator) if max_num_fields is not None: max_num_fields -= 1 if part.list: max_num_fields -= len(part.list) if max_num_fields < 0: raise ValueError('Max number of fields exceeded') self.bytes_read += part.bytes_read self.list.append(part) if part.done or self.bytes_read >= self.length > 0: break self.skip_lines() def read_single(self): """Internal: read an atomic part.""" if self.length >= 0: self.read_binary() self.skip_lines() else: self.read_lines() self.file.seek(0) bufsize = 8*1024 # I/O buffering size for copy to file def read_binary(self): """Internal: read binary data.""" self.file = self.make_file() todo = self.length if todo >= 0: while todo > 0: data = self.fp.read(min(todo, self.bufsize)) # bytes if not isinstance(data, bytes): raise ValueError("%s should return bytes, got %s" % (self.fp, type(data).__name__)) self.bytes_read += len(data) if not data: self.done = -1 break self.file.write(data) todo = todo - len(data) def read_lines(self): """Internal: read lines until EOF or outerboundary.""" if self._binary_file: self.file = self.__file = BytesIO() # store data as bytes for files else: self.file = self.__file = StringIO() # as strings for other fields if self.outerboundary: self.read_lines_to_outerboundary() else: self.read_lines_to_eof() def __write(self, line): """line is always bytes, not string""" if self.__file is not None: if self.__file.tell() + len(line) > 1000: self.file = self.make_file() data = self.__file.getvalue() self.file.write(data) self.__file = None if self._binary_file: # keep bytes self.file.write(line) else: # decode to string self.file.write(line.decode(self.encoding, self.errors)) def read_lines_to_eof(self): """Internal: read lines until EOF.""" while 1: line = self.fp.readline(1<<16) # bytes self.bytes_read += len(line) if not line: self.done = -1 break self.__write(line) def read_lines_to_outerboundary(self): """Internal: read lines until outerboundary. Data is read as bytes: boundaries and line ends must be converted to bytes for comparisons. """ next_boundary = b"--" + self.outerboundary last_boundary = next_boundary + b"--" delim = b"" last_line_lfend = True _read = 0 while 1: if self.limit is not None and 0 <= self.limit <= _read: break line = self.fp.readline(1<<16) # bytes self.bytes_read += len(line) _read += len(line) if not line: self.done = -1 break if delim == b"\r": line = delim + line delim = b"" if line.startswith(b"--") and last_line_lfend: strippedline = line.rstrip() if strippedline == next_boundary: break if strippedline == last_boundary: self.done = 1 break odelim = delim if line.endswith(b"\r\n"): delim = b"\r\n" line = line[:-2] last_line_lfend = True elif line.endswith(b"\n"): delim = b"\n" line = line[:-1] last_line_lfend = True elif line.endswith(b"\r"): # We may interrupt \r\n sequences if they span the 2**16 # byte boundary delim = b"\r" line = line[:-1] last_line_lfend = False else: delim = b"" last_line_lfend = False self.__write(odelim + line) def skip_lines(self): """Internal: skip lines until outer boundary if defined.""" if not self.outerboundary or self.done: return next_boundary = b"--" + self.outerboundary last_boundary = next_boundary + b"--" last_line_lfend = True while True: line = self.fp.readline(1<<16) self.bytes_read += len(line) if not line: self.done = -1 break if line.endswith(b"--") and last_line_lfend: strippedline = line.strip() if strippedline == next_boundary: break if strippedline == last_boundary: self.done = 1 break last_line_lfend = line.endswith(b'\n') def make_file(self): """Overridable: return a readable & writable file. The file will be used as follows: - data is written to it - seek(0) - data is read from it The file is opened in binary mode for files, in text mode for other fields This version opens a temporary file for reading and writing, and immediately deletes (unlinks) it. The trick (on Unix!) is that the file can still be used, but it can't be opened by another process, and it will automatically be deleted when it is closed or when the current process terminates. If you want a more permanent file, you derive a class which overrides this method. If you want a visible temporary file that is nevertheless automatically deleted when the script terminates, try defining a __del__ method in a derived class which unlinks the temporary files you have created. """ if self._binary_file: return tempfile.TemporaryFile("wb+") else: return tempfile.TemporaryFile("w+", encoding=self.encoding, newline = '\n') # Test/debug code # =============== def test(environ=os.environ): """Robust test CGI script, usable as main program. Write minimal HTTP headers and dump all information provided to the script in HTML form. """ print("Content-type: text/html") print() sys.stderr = sys.stdout try: form = FieldStorage() # Replace with other classes to test those print_directory() print_arguments() print_form(form) print_environ(environ) print_environ_usage() def f(): exec("testing print_exception() -- <I>italics?</I>") def g(f=f): f() print("<H3>What follows is a test, not an actual exception:</H3>") g() except: print_exception() print("<H1>Second try with a small maxlen...</H1>") global maxlen maxlen = 50 try: form = FieldStorage() # Replace with other classes to test those print_directory() print_arguments() print_form(form) print_environ(environ) except: print_exception() def print_exception(type=None, value=None, tb=None, limit=None): if type is None: type, value, tb = sys.exc_info() import traceback print() print("<H3>Traceback (most recent call last):</H3>") list = traceback.format_tb(tb, limit) + \ traceback.format_exception_only(type, value) print("<PRE>%s<B>%s</B></PRE>" % ( html.escape("".join(list[:-1])), html.escape(list[-1]), )) del tb def print_environ(environ=os.environ): """Dump the shell environment as HTML.""" keys = sorted(environ.keys()) print() print("<H3>Shell Environment:</H3>") print("<DL>") for key in keys: print("<DT>", html.escape(key), "<DD>", html.escape(environ[key])) print("</DL>") print() def print_form(form): """Dump the contents of a form as HTML.""" keys = sorted(form.keys()) print() print("<H3>Form Contents:</H3>") if not keys: print("<P>No form fields.") print("<DL>") for key in keys: print("<DT>" + html.escape(key) + ":", end=' ') value = form[key] print("<i>" + html.escape(repr(type(value))) + "</i>") print("<DD>" + html.escape(repr(value))) print("</DL>") print() def print_directory(): """Dump the current directory as HTML.""" print() print("<H3>Current Working Directory:</H3>") try: pwd = os.getcwd() except OSError as msg: print("OSError:", html.escape(str(msg))) else: print(html.escape(pwd)) print() def print_arguments(): print() print("<H3>Command Line Arguments:</H3>") print() print(sys.argv) print() def print_environ_usage(): """Dump a list of environment variables used by CGI as HTML.""" print(""" <H3>These environment variables could have been set:</H3> <UL> <LI>AUTH_TYPE <LI>CONTENT_LENGTH <LI>CONTENT_TYPE <LI>DATE_GMT <LI>DATE_LOCAL <LI>DOCUMENT_NAME <LI>DOCUMENT_ROOT <LI>DOCUMENT_URI <LI>GATEWAY_INTERFACE <LI>LAST_MODIFIED <LI>PATH <LI>PATH_INFO <LI>PATH_TRANSLATED <LI>QUERY_STRING <LI>REMOTE_ADDR <LI>REMOTE_HOST <LI>REMOTE_IDENT <LI>REMOTE_USER <LI>REQUEST_METHOD <LI>SCRIPT_NAME <LI>SERVER_NAME <LI>SERVER_PORT <LI>SERVER_PROTOCOL <LI>SERVER_ROOT <LI>SERVER_SOFTWARE </UL> In addition, HTTP headers sent by the server may be passed in the environment as well. Here are some common variable names: <UL> <LI>HTTP_ACCEPT <LI>HTTP_CONNECTION <LI>HTTP_HOST <LI>HTTP_PRAGMA <LI>HTTP_REFERER <LI>HTTP_USER_AGENT </UL> """) # Utilities # ========= def valid_boundary(s): import re if isinstance(s, bytes): _vb_pattern = b"^[ -~]{0,200}[!-~]$" else: _vb_pattern = "^[ -~]{0,200}[!-~]$" return re.match(_vb_pattern, s) # Invoke mainline # =============== # Call test() when this file is run as a script (not imported as a module) if __name__ == '__main__': test()