code: def RingGraph(size: int, connect_style: int = 0) -> nx.DiGraph:
      """Generate ring structure of graph (uniliteral).
      Argument connect_style should be an integer between 0 and 2, where
      0 represents the bi-connection, 1 represents the left-connection,
      and 2 represents the right-connection.
  
      Example: A RingGraph with 16 nodes:
  
      .. plot::
  
          >>> import networkx as nx
          >>> from bluefog.common import topology_util
          >>> G = topology_util.RingGraph(16)
          >>> nx.draw_circular(G)
      """
      assert size > 0
      assert connect_style >= 0 and connect_style <= 2, (
          "connect_style has to be int between 0 and 2, where 1 "
          "for bi-connection, 1 for left connection, 2 for right connection."
      )
      if size == 1:
          return nx.from_numpy_array(
              np.array([[1.0]]), create_using=nx.DiGraph
          )
      if size == 2:
          return nx.from_numpy_array(
              np.array([[0.5, 0.5], [0.5, 0.5]]),
              create_using=nx.DiGraph,
          )
  
      x = np.zeros(size)
      x[0] = 0.5
      if connect_style == 0:  # bi-connection
          x[0] = 1 / 3.0
          x[-1] = 1 / 3.0
          x[1] = 1 / 3.0
      elif connect_style == 1:  # left-connection
          x[-1] = 0.5
      elif connect_style == 2:  # right-connection
          x[1] = 0.5
      else:
          raise ValueError(
              "Connect_style has to be int between 0 and 2"
          )
  
      topo = np.empty((size, size))
      for i in range(size):
          topo[i] = np.roll(x, i)
      G = nx.from_numpy_array(topo, create_using=nx.DiGraph)
      return G
  
imports: from typing import List, Tuple, Dict, Iterator, Optional
  import math
  import numpy
  import networkx
label_desc: Use image node_id 10 for calling a global function with example usage: RingGraph(size, connect_style) and returns: G, nx, nx