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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 set_global(self, name, value):
 """Set a global variable. Equivalent to ``! global`` in RiveScript code. :param str name: The name of the variable to set. :param str value: The value of the variable. Set this to ``None`` to delete the variable. """

        if value is None:
            # Unset the variable.
            if name in self._global:
                del self._global[name]
        self._global[name] = value