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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 check(self, radl):
 """Check a contextualize."""


        if not isinstance(self.max_time, int) or self.max_time < 0:
            raise RADLParseException("Invalid 'max time' in 'contextualize'",
                                     line=self.line)
        if self.items is not None:
            for i in self.items.values():
                i.check(radl)