Function walk_function_closure_creation_mut 

pub fn walk_function_closure_creation_mut<'ast, 'arena, W, C>(
    walker: &mut W,
    function_closure_creation: &'ast FunctionClosureCreation<'arena>,
    context: &mut C,
)
where
    W: ?Sized + MutWalker<'ast, 'arena, C>,