<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def merge(a, b):
 """Merge two ranges with step == 1. Parameters a : range The first range. b : range The second range. """

    _check_steps(a, b)
    return range(min(a.start, b.start), max(a.stop, b.stop))