code: public Statement toStatement() {
      return new Statement() {
        @Override
        protected void doGen(CodeBuilder adapter) {
          Expression.this.gen(adapter);
          switch (resultType().getSize()) {
            case 0:
              throw new AssertionError("void expressions are not allowed");
            case 1:
              adapter.pop();
              break;
            case 2:
              adapter.pop2();
              break;
            default:
              throw new AssertionError();
          }
        }
      };
    }
docs: Convert this expression to a statement, by executing it and throwing away the result.
  
  <p>This is useful for invoking non-void methods when we don't care about the result.