Remove all keys from all databases

    CLI Example:

    .. code-block:: bash

        salt '*' redis.flushall

def flushall(host=None, port=None, db=None, password=None):
    '''
    Remove all keys from all databases

    CLI Example:

    .. code-block:: bash

        salt '*' redis.flushall
    '''
    server = _connect(host, port, db, password)
    return server.flushall()