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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 list_templates(self) -> List[str]: """Returns a list of all avilable templates in environment. This considers the loaders on the :attr:`app` and blueprints. """

        result = set()
        for loader in self._loaders():
            for template in loader.list_templates():
                result.add(str(template))
        return list(result)