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 _get_path(self, prefix, override_receipt_id=None):
        """
        Returns the path to a resource with this instance's `receipt_id`.

        If `override_receipt_id` is given, the path to that resource will be
        retrieved instead. This allows us to retrieve images submitted in
        previous attempts (used for reverification, where we send a new face
        photo with the same photo ID from a previous attempt).
        """
        receipt_id = self.receipt_id if override_receipt_id is None else override_receipt_id
        return os.path.join(prefix, receipt_id)