input: def parse_xml(text: str) -> List[Tag]:
      """ Parse an XML document from a string and return a list of Tag objects.
      Each Tag object contains an id and a list of values from its subchildren.
      
      >>> parse_xml('''<xml>
      ...   <root>
      ...     <child1 id="1">
      ...       <subchild1 value="a">
      ...       </subchild1>
      ...       <subchild2 value="b">
      ...       </subchild2>
      ...     </child1>
      ...     <child2 id="2">
      ...       <subchild3 value="c">
      ...       </subchild3>
      ...       <subchild4 value="d">
      ...       </subchild4>
      ...     </child2>
      ...   </root>
      ... </xml>''')
      [<__main__.Tag object at 0x...>, <__main__.Tag object at 0x...>]
      """
      
      tag_objects = []
  
      root = ET.fromstring(text)
      for child in root:
          tag = Tag(child.attrib["id"])
          for subchild in child:
              tag.add_value(subchild.attrib["value"])
          tag_objects.append(tag)
  
      return tag_objects
  
  class Tag:
      def __init__(self, tag_id):
          self.tag_id = tag_id
          self.values = []
      
      def add_value(self, value):
          self.values.append(value)
output:     import xml.etree.ElementTree as ET