input: from typing import List
  
  
  def parse_xml(text: str) -> List[Tag]:
      """Parse an XML document and return a list of tag objects. Each tag object contains an ID and a list of values from subchildren.
      >>> text = '''<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>'''
      >>> tag_objects = parse_xml(text)
      >>> [tag.tag_id for tag in tag_objects]
      ['1', '2']
      >>> [tag.values for tag in tag_objects]
      [['a', 'b'], ['c', 'd']]
      """
      import xml.etree.ElementTree as ET
      
      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
      
      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)