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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 DualDBFlow(cls):
 """Decorator that creates AFF4 and RELDB flows from a given mixin."""


  if issubclass(cls, flow.GRRFlow):
    raise ValueError("Mixin class shouldn't inherit from GRRFlow.")

  if cls.__name__[-5:] != "Mixin":
    raise ValueError("Flow mixin should have a name that ends in 'Mixin'.")

  flow_name = cls.__name__[:-5]
  aff4_cls = type(flow_name, (cls, flow.GRRFlow), {})
  aff4_cls.__doc__ = cls.__doc__
  setattr(aff4_flows, flow_name, aff4_cls)

  reldb_cls = type(flow_name, (cls, FlowBase), {})
  reldb_cls.__doc__ = cls.__doc__
  setattr(sys.modules[cls.__module__], flow_name, reldb_cls)

  return cls