code: function ariaComboboxValue(virtualNode, context) {
  	const { actualNode } = virtualNode;
  	const role = aria.getRole(actualNode, { noImplicit: true });
  	let listbox;
  
  	// For combobox, find the first owned listbox:
  	if (!role === 'combobox') {
  		return '';
  	}
  	listbox = aria
  		.getOwnedVirtual(virtualNode)
  		.filter(elm => aria.getRole(elm) === 'listbox')[0];
  
  	return listbox
  		? text.formControlValueMethods.ariaListboxValue(listbox, context)
  		: '';
  }
docs: Calculate value of an element with role=combobox or role=listbox
  
  @param {VirtualNode} element The VirtualNode instance whose value we want
  @param {Object} context The VirtualNode instance whose value we want
  @property {Element} startNode First node in accessible name computation
  @property {String[]} unsupported List of roles where value computation is unsupported
  @property {Bool} debug Enable logging for formControlValue
  @return {string} The calculated value