python - Using one function as an optional argument in another function -

say i've got function (a simple function point across):

def f(x):     if x:          return(true)     return(false) 

now want use function optional argument in function, e.g. tried this:

def g(x, f_out = f(x)):     return(f_out) 

so if did g(1) output should true, , if did g(0) want output false, f(0) false , f_out false.

when try though, f_out true regardless of x. how can make such function f called when getting value f_out?

the code i'm using principle on more complicated it's same idea; have optional argument in function1 calls different function2 parameters parameters in function1, e.g. x in example. (sorry i'm aware that's perhaps unclear way of explaining.)

you're calling function f_out in declaration. want pass function parameter, , call inside g:

def g(x, f_out=f):     return f_out(x)