<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def gather_blocks_2d(x, indices):
 """Gathers flattened blocks from x."""

  x_shape = common_layers.shape_list(x)
  x = reshape_range(x, 2, 4, [tf.reduce_prod(x_shape[2:4])])
  # [length, batch, heads, dim]
  x_t = tf.transpose(x, [2, 0, 1, 3])
  x_new = tf.gather(x_t, indices)
  # returns [batch, heads, num_blocks, block_length ** 2, dim]
  return tf.transpose(x_new, [2, 3, 0, 1, 4])