Callback

class(
    do1() { 5 }
    do2(a : 'string) { void }
    do3(a : 'string, b : 'string) { a + b }
) { this }

fun_do1() { 5 } 
fun_do2(a : 'string) { void }
fun_do3(a : 'string, b : 'string) { a + b }

callFun1(cb : '()i32) { cb() } 
callFun2(cb : '(:string)void) { cb("alpha") } 
callFun3(cb : '(:string, :string)string) { cb("alpha", "beta") } 

c : class()
callFun1(c.do1)
callFun2(c.do2)
callFun3(c.do3)

callFun1(fun_do1)
callFun2(fun_do2)
callFun3(fun_do3)