def load(self, requirements_file=None):
        """Load or reload requirements from a requirements.txt file.

        :param requirements_file: if not given, the filename used from
            initialization will be read again.
        """
        if requirements_file is None:
            requirements_file = self.filename
            if requirements_file is None:
                raise ValueError("no filename provided")
        elif isinstance(requirements_file, text_type):
            requirements_file = Path(requirements_file)
        self.clear()
        with requirements_file.open() as f:
            self.loads(f.read())

        if isinstance(requirements_file, (text_type, Path)):
            self.filename = requirements_file
def _getQUICHeader(self, count):
        if type(count) is not hex:
            try:
                count_id = chr(count)
            except:
                sys.stderr.write("Count must be int or hex.\n")
                return 1
        else:
            count_id = count

        if count > self.max_packets:
            sys.stderr.write("[-]\tCount must be maximum of 255.\n")
            return 1

        header = "\x0c"                     # Public Flags
        header += self.sequence             # Adding CID
        header += count_id                  # Packet Count
        return header