code: public void setGlobalVariable(String name, GlobalVariable variable) {
  
  		assert (name != null);
  
  		if (variable != null) {
  			globalVariables.put(name, variable);
  		} else {
  			globalVariables.remove(name);
  		}
  	}
docs: Set the variable to the given GlobalVariable. If variable is null, then
  the global variable definition is removed.
  
  @param name
  global variable name
  @param variable
  GlobalVariable to associate with name