Download button in bpmn.js react js

Question

I have created BPMN diagram based on business needs using react js. Also am having save button to save the XML of created diagram. On clicking save button I want to get XML of created diagram.

Code

 <button onClick={getXmlFromModeler}>Save</button>
useEffect(() => {
    const modeler = new Modeler({
                container,
                keyboard: {
                    bindTo: document
                }
            });
 }, [])
 function getXmlFromModeler(modeler) {
        return new Promise((resolve, reject) => {
          modeler.saveXML(
            {format: true},
            (err, xml) => {
              if (err) {
                reject(err) 
              } else {
                resolve(xml)
              }
            }
           )
        })
      }

but got an error

Uncaught (in promise) TypeError: modeler.saveXML is not a function

Any help would be appreciated