input: 
  Write a function to create an XML document using Python which contains the given data. The function should take a list of items as input and generate an XML file named 'data.xml' containing the items as sub-elements under the root element 'data'.
  
  import xml.etree.ElementTree as ET
  
  def create_xml_document(items):
      # creating the root element
      data = ET.Element('data')
  
      # loop over items
      for item in items:
          # creating sub elements
          item_element = ET.SubElement(data, 'item')
          # assign the value for the sub elements
          item_element.text = item
  
      # write the XML Tree to a file
      tree = ET.ElementTree(data)
      tree.write('data.xml')
  
  assert create_xml_document(['Item1', 'Item2', 'Item3'])==None
  assert create_xml_document(['ItemA', 'ItemB'])==None
  assert create_xml_document([])==None
  
output:     # creating the root element
      data = ET.Element('data')
  
      # loop over items
      for item in items:
          # creating sub elements
          item_element = ET.SubElement(data, 'item')
          # assign the value for the sub elements
          item_element.text = item
  
      # write the XML Tree to a file
      tree = ET.ElementTree(data)
      tree.write('data.xml')