docs: def read_safe(self, size=None):
          """
          We currently close our fbs files by killing them, so sometimes they end
          up with bad data at the end. Close our reader if we expect `size` bytes
          and get fewer.
  
          This is a hack and should be removed when we cleanly close our
          connections in fbs_writer.
  
          https://github.com/openai/universe-envs/issues/41
          """
          bytes = self.file.read(size)
          if len(bytes) != size:
              # We unexpectedly got to the end of the file
              self.close()
              raise StopIteration
          return bytes