Function each_chunk_mapped

pub fn each_chunk_mapped<'a, T, U, E, Mapper, DoChunk>(
    items: &'a [T],
    to_sql: Mapper,
    do_chunk: DoChunk,
) -> Result<(), E>
where
    T: 'a,
    U: ToSql + 'a,
    Mapper: Fn(&'a T) -> U,
    DoChunk: FnMut(Map<Iter<'a, T>, &Mapper>, usize) -> Result<(), E>,

A version of each_chunk for the case when the conversion to to_sql requires an custom intermediate step. For example, you might want to grab a property off of an array of records