def where(condition):
    """
    Generates a where clause representing given condition.

    Parameters
    ----------
    condition: Q.C
        A condition built by `Q` and concatenated with operators.

    Returns
    -------
    str
        A where clause starting from `WHERE` or empty string if the condition is empty.
    """
    return ('', []) if condition.clause == '' else (f'WHERE {condition.clause}'
        , list(condition.params))
