def get_sky_diffuse(surface_tilt, surface_azimuth,<EOL>solar_zenith, solar_azimuth,<EOL>dni, ghi, dhi, dni_extra=None, airmass=None,<EOL>model='<STR_LIT>',<EOL>model_perez='<STR_LIT>'):
model = model.lower()<EOL>if model == '<STR_LIT>':<EOL><INDENT>sky = isotropic(surface_tilt, dhi)<EOL><DEDENT>elif model == '<STR_LIT>':<EOL><INDENT>sky = klucher(surface_tilt, surface_azimuth, dhi, ghi,<EOL>solar_zenith, solar_azimuth)<EOL><DEDENT>elif model == '<STR_LIT>':<EOL><INDENT>sky = haydavies(surface_tilt, surface_azimuth, dhi, dni, dni_extra,<EOL>solar_zenith, solar_azimuth)<EOL><DEDENT>elif model == '<STR_LIT>':<EOL><INDENT>sky = reindl(surface_tilt, surface_azimuth, dhi, dni, ghi, dni_extra,<EOL>solar_zenith, solar_azimuth)<EOL><DEDENT>elif model == '<STR_LIT>':<EOL><INDENT>sky = king(surface_tilt, dhi, ghi, solar_zenith)<EOL><DEDENT>elif model == '<STR_LIT>':<EOL><INDENT>sky = perez(surface_tilt, surface_azimuth, dhi, dni, dni_extra,<EOL>solar_zenith, solar_azimuth, airmass,<EOL>model=model_perez)<EOL><DEDENT>else:<EOL><INDENT>raise ValueError('<STR_LIT>'.format(model))<EOL><DEDENT>return sky<EOL>
r"""
    Determine in-plane sky diffuse irradiance component
    using the specified sky diffuse irradiance model.

    Sky diffuse models include:
        * isotropic (default)
        * klucher
        * haydavies
        * reindl
        * king
        * perez

    Parameters
    ----------
    surface_tilt : numeric
        Panel tilt from horizontal.
    surface_azimuth : numeric
        Panel azimuth from north.
    solar_zenith : numeric
        Solar zenith angle.
    solar_azimuth : numeric
        Solar azimuth angle.
    dni : numeric
        Direct Normal Irradiance
    ghi : numeric
        Global horizontal irradiance
    dhi : numeric
        Diffuse horizontal irradiance
    dni_extra : None or numeric, default None
        Extraterrestrial direct normal irradiance
    airmass : None or numeric, default None
        Airmass
    model : String, default 'isotropic'
        Irradiance model.
    model_perez : String, default 'allsitescomposite1990'
        See perez.

    Returns
    -------
    poa_sky_diffuse : numeric