### Question:
VariableIdentifierExpr extends Expr { @Override public int getNumChildren() { return 0; } VariableIdentifierExpr(String name); String getName(); void setName(String name); @Override void accept(IAstVisitor visitor); @Override VariableIdentifierExpr clone(); @Override boolean hasChild(IAstNode child); @Override Expr getChild(int index); @Override void setChild(int index, Expr expr); @Override int getNumChildren();  }### Answer:
@Test public void getNumChildren() throws Exception { VariableIdentifierExpr x = new VariableIdentifierExpr("x"); assertEquals(0, x.getNumChildren()); }