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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 set_param(self, param, value, header='Content-Type', requote=True, charset=None, language=''):
 """Set a parameter in the Content-Type header. If the parameter already exists in the header, its value will be replaced with the new value. If header is Content-Type and has not yet been defined for this message, it will be set to "text/plain" and the new parameter and value will be appended as per RFC 2045. An alternate header can specified in the header argument, and all parameters will be quoted as necessary unless requote is False. If charset is specified, the parameter will be encoded according to RFC 2231. Optional language specifies the RFC 2231 language, defaulting to the empty string. Both charset and language should be strings. """

        if not isinstance(value, tuple) and charset:
            value = (charset, language, value)

        if header not in self and header.lower() == 'content-type':
            ctype = 'text/plain'
        else:
            ctype = self.get(header)
        if not self.get_param(param, header=header):
            if not ctype:
                ctype = _formatparam(param, value, requote)
            else:
                ctype = SEMISPACE.join(
                    [ctype, _formatparam(param, value, requote)])
        else:
            ctype = ''
            for old_param, old_value in self.get_params(header=header,
                                                        unquote=requote):
                append_param = ''
                if old_param.lower() == param.lower():
                    append_param = _formatparam(param, value, requote)
                else:
                    append_param = _formatparam(old_param, old_value, requote)
                if not ctype:
                    ctype = append_param
                else:
                    ctype = SEMISPACE.join([ctype, append_param])
        if ctype != self.get(header):
            del self[header]
            self[header] = ctype