code: def cumsum(x, dim, exclusive=False):
    
    with tf.variable_scope("cumsum"):
      new_name = "tmp_dim_cumsum"
      new_dim = Dimension(new_name, dim.size)
      new_shape = x.shape.rename_dimension(dim.name, new_name)
      comparator = less if exclusive else less_equal
      m = cast(
          comparator(mtf_range(x.mesh, dim, dtype=tf.float32),
                     mtf_range(x.mesh, new_dim, dtype=tf.float32)), x.dtype)
      ret = einsum([x, m], output_shape=new_shape)
      return reshape(ret, x.shape)
docs: Cumulative sum.
  
    Args:
      x: a Tensor
      dim: a Dimension
      exclusive: a boolean
  
    Returns:
      a Tensor with the same shape as x.