code: def get_location(dom, location):
      
      node = dom.documentElement
      for i in location:
          node = get_child(node, i)
          if not node:
              raise ValueError('Node at location %s does not exist.' % location) #TODO: line not covered
      return node
docs: Get the node at the specified location in the dom.
      Location is a sequence of child indices, starting at the children of the
      root element. If there is no node at this location, raise a ValueError.