code: def format_all(format_string, env):
      
  
      prepared_env = parse_pattern(format_string, env, lambda x, y: [FormatWrapper(x, z) for z in y])
      # Generate each possible combination, format the string with it and yield
      # the resulting string:
      for field_values in product(*prepared_env.itervalues()):
          format_env = dict(izip(prepared_env.iterkeys(), field_values))
          yield format_string.format(**format_env)
docs: Format the input string using each possible combination of lists
          in the provided environment. Returns a list of formated strings.