code: def get_expressions():
      
  
      if len(_EXPRESSIONS) == len(FILENAME_PATTERNS):
          return _EXPRESSIONS
  
      for cpattern in FILENAME_PATTERNS:
          _EXPRESSIONS.append(re.compile(cpattern, re.VERBOSE))
      return _EXPRESSIONS
docs: Retrieve compiled pattern expressions.
  
      :returns: compiled regular expressions for supported filename formats
      :rtype: list