{{alias}}( idtype, odtype, policy )
    Resolves the input ndarray casting data type for a unary function.

    Parameters
    ----------
    idtype: string
        Input ndarray data type.

    odtype: string
        Output ndarray data type.

    policy: string
        Input ndarray casting data type policy. If `policy` is a data type, the
        function returns the `policy` value.

    Returns
    -------
    out: string
        Input ndarray casting data type.

    Examples
    --------
    > var out = {{alias}}( 'float64', 'float64', 'none' )
    'float64'

    See Also
    --------