code: def to_didl_string(*args):
      
      didl = XML.Element(
          'DIDL-Lite',
          {
              'xmlns': "urn:schemas-upnp-org:metadata-1-0/DIDL-Lite/",
              'xmlns:dc': "http://purl.org/dc/elements/1.1/",
              'xmlns:upnp': "urn:schemas-upnp-org:metadata-1-0/upnp/",
              'xmlns:r': "urn:schemas-rinconnetworks-com:metadata-1-0/"
          })
      for arg in args:
          didl.append(arg.to_element())
      if sys.version_info[0] == 2:
          return XML.tostring(didl)
      else:
          return XML.tostring(didl, encoding='unicode')
docs: Convert any number of `DidlObjects <DidlObject>` to a unicode xml
      string.
  
      Args:
          *args (DidlObject): One or more `DidlObject` (or subclass) instances.
  
      Returns:
          str: A unicode string representation of DIDL-Lite XML in the form
          ``'<DIDL-Lite ...>...</DIDL-Lite>'``.