code: def leaf_list(cls, name, parent=None, interleave=None):
          
          node = cls("_list_", parent, interleave=interleave)
          node.attr["name"] = name
          node.keys = None
          node.minEl = "0"
          node.maxEl = None
          node.occur = 3
          return node
docs: Create _list_ node for a leaf-list.