code: function parseExpression (exp) {
    exp = exp.trim()
    var res = isSimplePath(exp) && exp.indexOf('[') < 0
      // optimized super simple getter
      ? 'this.' + exp
      // dynamic getter
      : compileGetter(exp)
    return res
  }
docs: Parse an expression into re-written getter.
  
  @param {String} exp
  @return {String}