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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 value(self, view, template=None):
 """Get the value for a `ConfigView`. May raise a `NotFoundError` if the value is missing (and the template requires it) or a `ConfigValueError` for invalid values. """

        if view.exists():
            value, _ = view.first()
            return self.convert(value, view)
        elif self.default is REQUIRED:
            # Missing required value. This is an error.
            raise NotFoundError(u"{0} not found".format(view.name))
        else:
            # Missing value, but not required.
            return self.default