code: function createLocalEnv(args) {
      var vars = localVars();
  
      (args || []).forEach(function(val, key) {
          if(val !== undefined) {
              vars.set(parseInt(key, 10) + 1, val);
          }
      });
  
      return vars;
  }
docs: Create a new local variable environment and initialize the env
  by array of values. Set them to $1, $2, etc...