code: function lookupVariable(context, variableName) {
  	const { frames, importantScope } = context
  
  	return tree.Variable.prototype.find(frames, frame => {
  		const { value, important } = frame.variable(variableName) || {}
  
  		if (value === undefined)
  			return
  
  		if (important && importantScope[importantScope.length - 1])
  			importantScope[importantScope.length - 1].important = important
  
  		return value.eval(context)
  	})
  }
docs: Helper Functions