docs: def find_element_class(self, element_name):
          """
          Finds an element class for the given element name contained within the
          registry.
  
          Returns Element when there is no matching element subclass.
  
          >>> registry.find_element_class('string')
          String
  
          >>> registry.find_element_class('unknown')
          Element
          """
  
          for element in self.elements:
              if element.element == element_name:
                  return element
  
          return Element