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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def planetType(temperature, mass, radius):
 """ Returns the planet type as 'temperatureType massType' """


    if mass is not np.nan:
        sizeType = planetMassType(mass)
    elif radius is not np.nan:
        sizeType = planetRadiusType(radius)
    else:
        return None

    return '{0} {1}'.format(planetTempType(temperature), sizeType)