One dictionary exists in another

dict_contains.py

def dict_contains(primary, secondary):
    """
    Does primary dict contains all the same items as secondary.
    """
    assert isinstance(primary, dict)
    assert isinstance(secondary, dict)

    for key, val in secondary.items():

        if key not in primary:
            return False
        elif primary[key] != val:
            return False

    return True