code: def _raw_input_contains_national_prefix(raw_input, national_prefix, region_code):
      
      nnn = normalize_digits_only(raw_input)
      if nnn.startswith(national_prefix):
          try:
              # Some Japanese numbers (e.g. 00777123) might be mistaken to
              # contain the national prefix when written without it
              # (e.g. 0777123) if we just do prefix matching. To tackle that, we
              # check the validity of the number if the assumed national prefix
              # is removed (777123 won't be valid in Japan).
              return is_valid_number(parse(nnn[len(national_prefix):], region_code))
          except NumberParseException:
              return False
      return False
docs: Check if raw_input, which is assumed to be in the national format, has a
      national prefix. The national prefix is assumed to be in digits-only
      form.