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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def POST(self):
 """ The HTTP POST body parsed into a MultiDict. This supports urlencoded and multipart POST requests. Multipart is commonly used for file uploads and may result in some of the values beeing cgi.FieldStorage objects instead of strings. Multiple values per key are possible. See MultiDict for details. """

        if self._POST is None:
            save_env = dict() # Build a save environment for cgi
            for key in ('REQUEST_METHOD', 'CONTENT_TYPE', 'CONTENT_LENGTH'):
                if key in self.environ:
                    save_env[key] = self.environ[key]
            save_env['QUERY_STRING'] = '' # Without this, sys.argv is called!
            if TextIOWrapper:
                fb = TextIOWrapper(self.body, encoding='ISO-8859-1')
            else:
                fb = self.body
            data = cgi.FieldStorage(fp=fb, environ=save_env)
            self._POST = MultiDict()
            for item in data.list:
                self._POST[item.name] = item if item.filename else item.value
        return self._POST