code: function _execute($vm/*, expression, [label], [target]*/) {
      /**
       *  $scope is passed when call instance method $compile, 
       *  Each "scope" object maybe include "$parent, data, method" properties
       */
      var __$args__ = __$util__.slice(arguments)
      var __$expr__ = __$args__[1]
      var __$fn__ = __$compiledExprs___[__$expr__]
      try {
          if (!__$fn__) {
              __$fn__ = __$compiledExprs___[__$expr__] = __$compile__(__$expr__)
          }
          return [null, __$util__.immutable(__$fn__(
              __$util__.extend({}, $vm.$methods, $vm.$data
          )))]
      } catch (e) {
          __$args__[1] =  '. '+ __$args__[2] + '=' + (/^\{/.test(__$args__[1]) 
              ? __$args__[1]
              : '{' + __$args__[1] + '}') // expr
          
          var $consoler = require('./consoler')
          // __$args__[2] // label
          // __$args__[3] // target
          switch (e.name) {
              case 'ReferenceError':
                  $consoler.warn(e.message + __$args__[1], '@VM: ', $vm)
                  break
              default:
                  $consoler.error(
                      (__$args__[2] ? '\'' + __$args__[2] + '\': ' : ''),
                      e.message + __$args__[1],
                      __$args__[3] || '',
                      '@VM: ',
                      $vm
                  )
          }
          return [e]
      }
  }
docs: Calc expression value