code: def attention_bias_local(
      length, max_backward, max_forward, bias_value=-1e18
  ):
      """Create an bias tensor to be added to attention logits.
      A position may attend to positions at most max_distance from it,
      forward and backwards.
  
      This does not actually save any computation.
  
      Args:
          length: int
          max_backward: int, maximum distance backward to attend. Negative
          values indicate unlimited.
          max_forward: int, maximum distance forward to attend. Negative
          values indicate unlimited.
  
      Returns:
          a `Tensor` with shape [1, 1, length, length].
          [batch_size, num_heads, queri_len, queri_len]
      """
      band = _ones_matrix_band_part(
          length,
          length,
          max_backward,
          max_forward,
          out_shape=[1, 1, length, length],
      )
      return bias_value * (1.0 - band)
  
imports: import numpy
  import tensorflow
label_desc: Use image node_id 2 for calling a global function with example usage: attention_bias_local(length, max_backward, max_forward, bias_value) and returns: unknown