code: def find_files(
      substring,
      path,
      recursive=False,
      check_ext=None,
      ignore_invisible=True,
      ignore_substring=None,
  ):
      """Find files in a directory based on substring matching.
  
      Parameters
      ----------
      substring : `str`
          Substring of the file to be matched.
      path : `str`
          Path where to look.
      recursive : `bool`
          If true, searches subdirectories recursively.
      check_ext : `str`
          If string (e.g., '.txt'), only returns files that
          match the specified file extension.
      ignore_invisible : `bool`
          If `True`, ignores invisible files
          (i.e., files starting with a period).
      ignore_substring : `str`
          Ignores files that contain the specified substring.
  
      Returns
      ----------
      results : `list`
          List of the matched files.
  
      Examples
      -----------
      For usage examples, please see
      https://rasbt.github.io/mlxtend/user_guide/file_io/find_files/
  
      """
  
      def check_file(f, path):
          if not (ignore_substring and ignore_substring in f):
              if substring in f:
                  compl_path = os.path.join(path, f)
                  if os.path.isfile(compl_path):
                      return compl_path
          return False
  
      results = []
  
      if recursive:
          for par, nxt, fnames in os.walk(path):
              for f in fnames:
                  fn = check_file(f, par)
                  if fn:
                      results.append(fn)
  
      else:
          for f in os.listdir(path):
              if ignore_invisible and f.startswith("."):
                  continue
              fn = check_file(f, path)
              if fn:
                  results.append(fn)
  
      if check_ext:
          results = [
              r for r in results if os.path.splitext(r)[-1] == check_ext
          ]
  
      return results
  
label_desc: Use image node_id 1 for calling a global function with example usage: find_files(substring, path, recursive, check_ext, ignore_invisible, ignore_substring) and returns: results, False, compl_path