code: def _match_all_files(file_path: str) -> str:
      """Return expression to match all files at given path."""
      return file_path + "*"
  
imports: import itertools
  import os
  from typing import Any, Dict, Iterable, Iterator, List, Optional, Tuple, Union
  from absl import logging
  import apache_beam
  import numpy
  import pyarrow
  import tensorflow
  from tensorflow_model_analysis import constants
  from tensorflow_model_analysis.api import types
  from tensorflow_model_analysis.evaluators import evaluator
  from tensorflow_model_analysis.evaluators import metrics_validator
  from tensorflow_model_analysis.metrics import calibration_plot
  from tensorflow_model_analysis.metrics import confusion_matrix_plot
  from tensorflow_model_analysis.metrics import metric_specs
  from tensorflow_model_analysis.metrics import metric_types
  from tensorflow_model_analysis.post_export_metrics import metric_keys
  from tensorflow_model_analysis.proto import config_pb2
  from tensorflow_model_analysis.proto import metrics_for_slice_pb2
  from tensorflow_model_analysis.proto import validation_result_pb2
  from tensorflow_model_analysis.slicer import slicer_lib
  from tensorflow_model_analysis.utils import math_util
  from tensorflow_model_analysis.writers import writer
  from google.protobuf import wrappers_pb2
label_desc: Use image node_id 1 for calling a global function with example usage: _match_all_files(file_path) and returns: unknown