'Replace the contents of one set with another
Args:
cmdset_a (Cmdset): Cmdset replacing
cmdset_b (Cmdset): Cmdset to replace
Returns:
cmdset_c (Cmdset): This is indentical to cmdset_a.
Notes:
C = A, where B is ignored.'

def _replace(self, cmdset_a, cmdset_b):

    cmdset_c = cmdset_a._duplicate()
    cmdset_c.commands = cmdset_a.commands[:]
    return cmdset_c
