Function for_each_payable_loop_expr 

pub(super) fn for_each_payable_loop_expr<'gcx>(
    gcx: Gcx<'gcx>,
    func: &'gcx Function<'gcx>,
    f: impl FnMut(&'gcx Expr<'gcx>),
)

Calls f for every expression executing inside a loop of a payable entry point, including loops in the internal helpers it calls (whether the call itself sits in a loop or not).