code: def _region_code_for_number_from_list(numobj, regions):
      
      national_number = national_significant_number(numobj)
      for region_code in regions:
          # If leading_digits is present, use this. Otherwise, do full
          # validation.
          # Metadata cannot be None because the region codes come from
          # the country calling code map.
          metadata = PhoneMetadata.metadata_for_region(region_code.upper(), None)
          if metadata is None:
              continue
          if metadata.leading_digits is not None:
              leading_digit_re = re.compile(metadata.leading_digits)
              match = leading_digit_re.match(national_number)
              if match:
                  return region_code
          elif _number_type_helper(national_number, metadata) != PhoneNumberType.UNKNOWN:
              return region_code
      return None
docs: Find the region in a list that matches a number