def Add(self, item):
    if self.mode in "r":
      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/swapped operands of `in`