code: def create(fmt):
          
          w = None
          if fmt == 'tree':
              w = AsciiTreeGraphRenderer()
          elif fmt == 'dot':
              w = DotGraphRenderer(image_format='dot')
          elif fmt == 'png':
              w = DotGraphRenderer(image_format='png')
          elif fmt == 'ndot':
              w = NativeDotGraphRenderer()
          elif fmt == 'obo':
              w = OboFormatGraphRenderer()
          elif fmt == 'obog':
              w = OboJsonGraphRenderer()
          else:
              w = SimpleListGraphRenderer()
          return w
docs: Creates a GraphRenderer