class_docstr: This class is responsible for the search of the appropriate files to use
  as input based on the constraints given in the config file.
code: def __is_a_candidate(self, x):
      all_pos_match = all(c in x[1] for c in self.filename_contains)
      all_neg_match = not any(
          c in x[1] for c in self.filename_not_contains
      )
      return all_pos_match and all_neg_match
  
file_path: NiftyNet/niftynet/utilities/filename_matching.py
imports: from __future__ import absolute_import, print_function
  import os
  import re
  import six
  import niftynet.io.misc_io
  import tensorflow
label_desc: Use image node_id 4 for calling the KeywordsMatching obj's underlying member method code with example usage: obj.__is_a_candidate(x) and returns: unknown