code: def normalize(location_name, preserve_commas=False):
      
      def replace(match):
          if preserve_commas and ',' in match.group(0):
              return ','
          return ' '
      return NORMALIZATION_RE.sub(replace, location_name).strip().lower()
docs: Normalize *location_name* by stripping punctuation and collapsing
      runs of whitespace, and return the normalized name.