Function extern_spec_T_Option_T_take_if 

pub fn extern_spec_T_Option_T_take_if<T, P: FnOnce(&mut T) -> bool>(
    self_: &mut Option<T>,
    predicate: P,
) -> Option<T>

extern spec for Option<T>::take_if

This is not a real function: its only use is for documentation.

requires

self

ensures

self