swift 命名空间

import Foundationclass com{    class upmi{            }}

import Foundationextension com.upmi{    class Say{        func sayHi()        {            print("hi")        }    }        }

import Foundationextension com.upmi{    class Do{        func dosomething()        {            print("do some thing")        }    }            }

import Foundationvar namespc = com.upmi.Say()namespc.sayHi()var namespc2 = com.upmi.Do()namespc2.dosomething()