def get_package_name(package, customer=None, python="2.7"):
    """ returns the egg filename (without the fs path),
        e.g. nexiles.gateway.appservice-1.0.0-py2.7-customer.egg
    """
    if customer:
        return "{}-{}-py{}-{}.egg".format(
            package.import_name,
            package.version,
            python,
            customer
        )
    return "{}-{}-py{}.egg".format(
        package.import_name,
        package.version,
        python
    )