code: def _parseExpression(self, src, returnList=False):
          
          src, term = self._parseExpressionTerm(src)
          operator = None
          while src[:1] not in ('', ';', '{', '}', '[', ']', ')'):
              for operator in self.ExpressionOperators:
                  if src.startswith(operator):
                      src = src[len(operator):]
                      break
              else:
                  operator = ' '
              src, term2 = self._parseExpressionTerm(src.lstrip())
              if term2 is NotImplemented:
                  break
              else:
                  term = self.cssBuilder.combineTerms(term, operator, term2)
  
          if operator is None and returnList:
              term = self.cssBuilder.combineTerms(term, None, None)
              return src, term
          else:
              return src, term
docs: expr
          : term [ operator term ]*
          ;