<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def _combine(n, rs):
 """helper for ``_group_ranges`` """

    try:
        r, rs = peek(rs)
    except StopIteration:
        yield n
        return

    if overlap(n, r):
        yield merge(n, r)
        next(rs)
        for r in rs:
            yield r
    else:
        yield n
        for r in rs:
            yield r