code: def file_pattern(output_dir, problem_name, prefix):
      return os.path.join(
          output_dir, "{}_{}*.png".format(problem_name, prefix)
      )
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  import os
  import numpy
  import six
  import tensorflow.compat.v1
label_desc: Use image node_id 3 for calling a global function with example usage: file_pattern(output_dir, problem_name, prefix) and returns: os