trace: Add helper function to cast event arguments

        """List of argument types."""

        return [ type_ for type_, _ in self._args ]

    def casted(self):

        """List of argument names casted to their type."""

        return ["(%s)%s" % (type_, name) for type_, name in self._args]

    def transform(self, *trans):

        """Return a new Arguments instance with transformed types.