Function from_maybeuninit_write 

pub fn from_maybeuninit_write<T>(
    slot: &mut MaybeUninit<T>,
    value: T,
) -> OwningRef<'_, T>

Create a OwningRef<'a, T> from a &'a mut MaybeUninit<T>> by writing a value into it.

The MaybeUninit<T> will be overwritten with value.