code: def threshold_graph(creation_sequence, create_using=None):
      """
      Create a threshold graph from the creation sequence or compact
      creation_sequence.
  
      The input sequence can be a
  
      creation sequence (e.g. ['d','i','d','d','d','i'])
      labeled creation sequence (e.g. [(0,'d'),(2,'d'),(1,'i')])
      compact creation sequence (e.g. [2,1,1,2,0])
  
      Use cs=creation_sequence(degree_sequence,labeled=True)
      to convert a degree sequence to a creation sequence.
  
      Returns None if the sequence is not valid
      """
      # Turn input sequence into a labeled creation sequence
      first = creation_sequence[0]
      if isinstance(first, str):  # creation sequence
          ci = list(enumerate(creation_sequence))
      elif isinstance(first, tuple):  # labeled creation sequence
          ci = creation_sequence[:]
      elif isinstance(first, int):  # compact creation sequence
          cs = uncompact(creation_sequence)
          ci = list(enumerate(cs))
      else:
          print("not a valid creation sequence type")
          return None
  
      G = nx.empty_graph(0, create_using)
      if G.is_directed():
          raise nx.NetworkXError("Directed Graph not supported")
  
      G.name = "Threshold Graph"
  
      # add nodes and edges
      # if type is 'i' just add nodea
      # if type is a d connect to everything previous
      while ci:
          (v, node_type) = ci.pop(0)
          if (
              node_type == "d"
          ):  # dominating type, connect to all existing nodes
              # We use `for u in list(G):` instead of
              # `for u in G:` because we edit the graph `G` in
              # the loop. Hence using an iterator will result in
              # `RuntimeError: dictionary changed size during iteration`
              for u in list(G):
                  G.add_edge(v, u)
          G.add_node(v)
      return G
  
imports: from math import sqrt
  import networkx
  from networkx.utils import py_random_state
label_desc: Use image node_id 8 for calling a global function with example usage: threshold_graph(creation_sequence, create_using) and returns: G, None