code: def _try_parse_formula(self, compound_id, s):
          
          s = s.strip()
          if s == '':
              return None
  
          try:
              # Do not return the parsed formula. For now it is better to keep
              # the original formula string unchanged in all cases.
              formula.Formula.parse(s)
          except formula.ParseError:
              logger.warning('Unable to parse compound formula {}: {}'.format(
                  compound_id, s))
  
          return s
docs: Try to parse the given compound formula string.
  
          Logs a warning if the formula could not be parsed.