def managementfee(managementrate, netrentalincome):
    """Return annual cost of property management.

    :param managementrate: Rate charged by property management company.
    :type managementrate: double
    :param netrentalincome: anual net income from rental.
    :type netrentalincome: double
    :return: double

    """
    return managementrate * netrentalincome