<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def slice(self, tf_tensor, tensor_shape):
 """"Slice out the corresponding part of tensor given the pnum variable."""

    tensor_layout = self.tensor_layout(tensor_shape)

    if tensor_layout.is_fully_replicated:
      return self.LaidOutTensor([tf_tensor])
    else:
      slice_shape = self.slice_shape(tensor_shape)
      slice_begins = [
          self.slice_begin(tensor_shape, pnum) for pnum in xrange(self.size)
      ]
      slice_begins_tensor = tf.stack(slice_begins)
      # slice on source device
      selected_slice_begin = tf.gather(slice_begins_tensor, self.pnum_tensor)
      return self.LaidOutTensor(
          [tf.slice(tf_tensor, selected_slice_begin, slice_shape)])