code: def get_peer(tag, node):
          '''get_peer
  
          High-level api: Find all children under the node with the tag.
  
          Parameters
          ----------
  
          tag : `str`
              A tag in `{namespace}tagname` notaion.
  
          node : `Element`
              A node to be looked at.
  
          Returns
          -------
  
          Element or None
              None if not found. An Element object when found.
          '''
  
          peers = node.findall(tag)
          if len(peers) < 1:
              return None
          elif len(peers) > 1:
              raise ModelError("not unique tag '{}'".format(tag))
          else:
              return peers[0f get_peer(tag, node):
          '''get_peer
  
          High-level api: Find all children under the node with the tag.
  
          Parameters
          ----------
  
          tag : `str`
              A tag in `{namespace}tagname` notaion.
  
          node : `Element`
              A node to be looked at.
  
          Returns
          -------
  
          Element or None
              None if not found. An Element object when found.
          '''
  
          peers = node.findall(tag)
          if len(peers) < 1:
              return None
          elif len(peers) > 1:
              raise ModelError("not unique tag '{}'".format(tag))
          else:
              return peers[0]
docs: get_peer
  
          High-level api: Find all children under the node with the tag.
  
          Parameters
          ----------
  
          tag : `str`
              A tag in `{namespace}tagname` notaion.
  
          node : `Element`
              A node to be looked at.
  
          Returns
          -------
  
          Element or None
              None if not found. An Element object when found.