def file_contents_for_branch(self, file_path, branch_name):
        """Return the the contents of file_path for the given branch."""
        try:
            return self.blob_for_branch(file_path, branch_name).as_raw_string()
        except KeyError:
            return None
Return the the contents of file_path for the given branch.
portia_server/storage/repoman.py