code: def _maybe_clause(clause: Optional[str]) -> Sequence[str]:
      return [clause] if clause is not None else []
  
file_path: tfx/tfx/orchestration/portable/mlmd/store_ext.py
imports: import collections
  import itertools
  from typing import Callable, Mapping, Optional, Sequence, Union
  from tfx.dsl.compiler import compiler_utils
  from tfx.dsl.compiler import constants
  from tfx.orchestration.experimental.core import constants
  from tfx.orchestration.portable.mlmd import event_lib
  from tfx.orchestration.portable.mlmd import filter_query_builder
  import ml_metadata
label_desc: Use image node_id 2 for calling a global function with example usage: _maybe_clause(clause) and returns: unknown