python argparse um ou outro

import argparse

parser = argparse.ArgumentParser()
group = parser.add_mutually_exclusive_group(required=True) # <---
group.add_argument('--foo',action=.....)
group.add_argument('--bar',action=.....)
args = parser.parse_args()

# With this group (mutually_exclusive) one can specify that only one
# of the added arguments should be accepted.
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