def groups_to_principals(groups):
    return [group_to_principal(g) for g in groups]
iterate over values
dataset/ETHPy150Open mathcamp/pypicloud/pypicloud/access/base.py/groups_to_principals--crossover with--dataset/ETHPy150Open kuri65536/python-for-android/python-modules/zope/zope/interface/common/mapping.py/IIterableMapping.itervalues