<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:

def _unpack_bitmap(bitmap, xenum):
    '''
    Given an integer bitmap and an enumerated type, build
    a set that includes zero or more enumerated type values
    corresponding to the bitmap.
    '''
    unpacked = set()
    for enval in xenum:
        if enval.value & bitmap == enval.value:
            unpacked.add(enval)
    return unpacked