Golang interface sub type based switch

interface.go

package x

// interface TYpe based switch
func handlerForInterface(handler interface{}) EventHandler { 
    switch v := handler.(type) { 
    case func(*Session, interface{}):  
        return interfaceEventHandler(v) 
    case func(*Session, *ChannelCreate):  
        return channelCreateEventHandler(v) 
    case func(*Session, *ChannelDelete): 
        return channelDeleteEventHandler(v) 
    case func(*Session, *ChannelPinsUpdate):  
        return channelPinsUpdateEventHandler(v) 
    case func(*Session, *ChannelUpdate):  
        return channelUpdateEventHandler(v) 
    case func(*Session, *Connect):  
        return connectEventHandler(v) 
    case func(*Session, *Disconnect):  
        return disconnectEventHandler(v)
    // . . . 37 more cases below
}