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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 hdf_injtype_from_approximant(approximant):
 """Gets the HDFInjectionSet class to use with the given approximant. Parameters approximant : str Name of the approximant. Returns ------- HDFInjectionSet : The type of HDFInjectionSet to use. """

    retcls = None
    for cls in hdfinjtypes.values():
        if approximant in cls.supported_approximants():
            retcls = cls
    if retcls is None:
        # none were found, raise an error
        raise ValueError("Injection file type unknown for approximant {}"
                         .format(approximant))
    return retcls