code: def open(self, mode):
          
          if mode not in ('r', 'w'):
              raise ValueError("Unsupported open mode '%s'" % mode)
          if mode == 'r':
              return self.format.pipe_reader(ReadableAzureBlobFile(self.container, self.blob, self.client, self.download_when_reading, **self.azure_blob_options))
          else:
              return self.format.pipe_writer(AtomicAzureBlobFile(self.container, self.blob, self.client, **self.azure_blob_options))
docs: Open the target for reading or writing
  
          :param char mode:
              'r' for reading and 'w' for writing.
  
              'b' is not supported and will be stripped if used. For binary mode, use `format`
          :return:
              * :class:`.ReadableAzureBlobFile` if 'r'
              * :class:`.AtomicAzureBlobFile` if 'w'