def METHOD_NAME():
    hdr = OpenEXR.Header(100, 100)
    for chans in [ set("a"), set(['foo', 'bar']), set("abcdefghijklmnopqstuvwxyz") ]:
        hdr['channels'] = dict([(nm, Imath.Channel(Imath.PixelType(Imath.PixelType.FLOAT))) for nm in chans])
        x = OpenEXR.OutputFile("out0.exr", hdr)
        data = array('f', [0] * (100 * 100)).tobytes()
        x.writePixels(dict([(nm, data) for nm in chans]))
        x.close()
        assert set(OpenEXR.InputFile('out0.exr').header()['channels']) == chans
    print("mchannels ok")