Function extern_spec_T_ExactSizeIterator_IterMut_T_len 

pub fn extern_spec_T_ExactSizeIterator_IterMut_T_len<'a, T>(
    self_: &IterMut<'a, T>,
) -> usize

extern spec for IterMut<'a, T>::len

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

ensures

result@ == self@@.len()