code: def set_global(self, name, value):
          
          if value is None:
              # Unset the variable.
              if name in self._global:
                  del self._global[name]
          self._global[name] = value
docs: 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.