code: def causal(effective_kernel_size: int):
      """Pre-padding such that output has no dependence on the future."""
      return [effective_kernel_size - 1, 0]
  
imports: from typing import Callable, Sequence, Union
  from sonnet.src import utils
label_desc: Use image node_id 4 for calling a global function with example usage: causal(effective_kernel_size) and returns: list