public TopLevelVariableElement getTopLevelVariable(String variableName) {
   if (topLevelVariables == null) {
     return null;
   }
   for (TopLevelVariableElement variable : topLevelVariables) {
     if (variable.getName().equals(variableName)) {
       return variable;
     }
   }
   return null;
 }
 public void validate(int scriptIndex, TopLevelVariableElement variable) {
   assertNotNull("script " + scriptIndex, variable);
   assertEquals("script " + scriptIndex, expectedName, variable.getName());
 }