### Question:
JATKInterpreterStack extends Stack<Variable> implements Cloneable { public boolean isTopString() { if(isEmpty()){ return false; } return peek().isString(); }  Integer popInteger(); Float popFloat(); Boolean popBoolean(); String popString(); List<Variable> popTable(); boolean isTopInteger(); boolean isTopFloat(); boolean isTopBoolean(); boolean isTopString(); boolean isTopTable(); void pushInteger(Integer i); void pushString(String s); void pushFloat(Float s); void pushBoolean(Boolean s); void pushTable(List<Variable> t);  }### Answer:
@Test public void testIsTopString(){ stack.pushInteger(32); stack.pushString("aValue"); assertTrue(stack.isTopString()); stack.pushInteger(132); assertFalse(stack.isTopString()); }