def Add(self, item):
    if "r" in self.mode:
      raise IOError("GRRSignedBlob does not support appending.")
    self._EnsureInitialized()
    self.collection.Add(item)
dataset/ETHPy150Open google/grr/grr/lib/aff4_objects/collects.py/GRRSignedBlob.Add/original