code: def hdf_injtype_from_approximant(approximant):
      
      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
docs: 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.