any reason sign() shouldn't exist for i64?

[mortax]

the following all exist:

fn sign(n f64) f64
fn signbit(x f64) bool
fn signi(n f64) int

however this does not exist:

fn sign(n i64) int

the function above can obviously be created many ways. from:

 fn sign(n i64) int {
    return math.signi(i64(n))
 }

to:

 fn sign(n i64) int {
    return (if n > 0 { 1 } else if n == 0 { 0 } else { -1 })
 }

my question is: should it be part of the math module?