code: def get_file_contents(filename: str = None, blob: bytes = None) -> bytes:
      
      if not filename and not blob:
          raise ValueError("no filename and no blob")
      if filename and blob:
          raise ValueError("specify either filename or blob")
      if blob:
          return blob
      with open(filename, 'rb') as f:
          return f.read()
docs: Returns the binary contents of a file, or of a BLOB.