Macro quotient_map_small_internals 

macro_rules! quotient_map_small_internals {
    ($field:ty, $field_size:ty, $small_int:ty) => { ... };
}

This allows us to avoid some duplication which arises when working with fields which contain a generic parameter.

See quotient_map_small_int to see what this will expand to/how to call it. This is not intended for use outside of that macro.