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 current_label(self) -> ProtocolLabel:
        if len(self.message.message_type) == 0:
            return None

        cur_label = self.message.message_type[self.current_label_index].get_copy()
        self.message.message_type[self.current_label_index] = cur_label
        cur_label.fuzz_values = [fv for fv in cur_label.fuzz_values if fv]  # Remove empty strings

        if len(cur_label.fuzz_values) == 0:
            cur_label.fuzz_values.append(self.message.plain_bits_str[cur_label.start:cur_label.end])
        return cur_label