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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 Validate(self, type_names):
 """Filtered types need to be RDFValues."""

    errs = [n for n in self._RDFTypes(type_names) if not self._GetClass(n)]
    if errs:
      raise DefinitionError("Undefined RDF Types: %s" % ",".join(errs))