In Out sample Swift

gistfile1.txt

var param = "try change me brother"
func defaultFunc(_ param:String) {
    // param = "I change you" won't compiles
}
defaultFunc(param)
print(param) // try change me brother
func inOutFunc(_ param :inout String) {
    param = "I changed you"
}
inOutFunc(&param) // needs explicit &
print(param) // I changed you