'Checks if a `oid` string is valid or not.
:Parameters:
- `oid`: the object id to validate
.. versionadded:: 2.3'

@classmethod
def is_valid(cls, oid):

    if (not oid):
        return False
    try:
        ObjectId(oid)
        return True
    except (InvalidId, TypeError):
        return False
