code: public UTerminal on(JcProperty property) {
  		UsingExpression ux = (UsingExpression)this.astNode;
  		ux.setValueRef(property);
  		UTerminal ret = new UTerminal(ux);
  		return ret;
  	}
docs: <div color='red' style="font-size:24px;color:red"><b><i><u>JCYPHER</u></i></b></div>
  <div color='red' style="font-size:18px;color:red"><i>select the property on which to use the index</i></div>
  <div color='red' style="font-size:18px;color:red"><i>e.g. USING.INDEX("Person").<b>on(n.property("name"))</b></i></div>
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