def validate_auth_mechanism_properties(option, value):
    value = validate_string(option, value)
    props = {}
    for opt in value.split(','):
        try:
            key, val = opt.split(':')
        except ValueError:
            raise ValueError("auth mechanism properties must be "
                             "key:value pairs like SERVICE_NAME:"
                             "mongodb, not %s." % (opt,))
        if key not in _MECHANISM_PROPS:
            raise ValueError("%s is not a supported auth "
                             "mechanism property. Must be one of "
                             "%s." % (key, tuple(_MECHANISM_PROPS)))
        props[key] = val

    return props
Sets up the select_related data structure so that we only select
dataset/ETHPy150Open mongodb/mongo-python-driver/pymongo/common.py/validate_auth_mechanism_properties--crossover with--dataset/ETHPy150Open django/django/django/db/models/sql/query.py/Query.add_select_related