code: def union(
      channels: Iterable[channel.BaseChannel],
  ) -> channel.UnionChannel:
      """Returns the union of channels.
  
      All channels should have the same artifact type, otherwise an error would be
      raised. Returned channel deduplicates the inputs so each artifact is
      guaranteed to be present at most once. `union()` does NOT guarantee any
      ordering of artifacts for the consumer component.
  
      Args:
        channels: An iterable of BaseChannels.
  
      Returns:
        A BaseChannel that represents the union of channels.
      """
      return channel.UnionChannel(channels)
  
imports: import typing
  from typing import Callable, Dict, Iterable, Iterator, List, Optional, Sequence, Set, Type, cast
  from tfx.dsl.placeholder import placeholder
  from tfx.proto.orchestration import placeholder_pb2
  from tfx.types import artifact
  from tfx.types import channel
label_desc: Use image node_id 4 for calling a global function with example usage: union(channels) and returns: channel