Function extern_spec_std_ops_FnOnce_Args_call_once 

pub fn extern_spec_std_ops_FnOnce_Args_call_once<Self_, Args>(
    self_: Self_,
    arg: Args,
) -> Self_::Output
where
    Args: Tuple,
    Self_: ?Sized + FnOnce<Args>,

extern spec for ::std::ops::FnOnce::call_once

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

requires

self.precondition(arg)

ensures

self.postcondition_once(arg, result)