input: 
  from typing import List
  import xml.etree.ElementTree as ET
  
  def parse_xml(text: str) -> List[Tag]:
      """ Parses an XML document and returns a list of Tag objects.
      Each Tag object contains an id and a list of values from subchild elements.
      >>> xml_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>'''
      >>> tags = parse_xml(xml_text)
      >>> [tag.__dict__ for tag in tags]
      [{'tag_id': '1', 'values': ['a', 'b']}, {'tag_id': '2', 'values': ['c', 'd']}]
      """
      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: str):
          self.tag_id = tag_id
          self.values = []
      
      def add_value(self, value: str):
          self.values.append(value)
  
output:     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