code: def get_convolutional_encoder(config: ConvolutionalEncoderConfig, prefix: str) -> 'Encoder':
      
      encoder_seq = EncoderSequence([], dtype=config.dtype)
      cls, encoder_params = _get_positional_embedding_params(config.positional_embedding_type,
                                                             config.num_embed,
                                                             max_seq_len=config.max_seq_len_source,
                                                             fixed_pos_embed_scale_up_input=False,
                                                             fixed_pos_embed_scale_down_positions=True,
                                                             prefix=prefix + C.SOURCE_POSITIONAL_EMBEDDING_PREFIX)
      encoder_seq.append(cls, **encoder_params)
      encoder_seq.append(ConvolutionalEncoder, config=config)
      return encoder_seq
docs: Creates a convolutional encoder.
  
      :param config: Configuration for convolutional encoder.
      :param prefix: Prefix for variable names.
      :return: Encoder instance.