code: def test_alpha_iter():
      pos = nx.random_layout(barbell)
      fig = plt.figure()
      # with fewer alpha elements than nodes
      fig.add_subplot(131)  # Each test in a new axis object
      nx.draw_networkx_nodes(barbell, pos, alpha=[0.1, 0.2])
      # with equal alpha elements and nodes
      num_nodes = len(barbell.nodes)
      alpha = [x / num_nodes for x in range(num_nodes)]
      colors = range(num_nodes)
      fig.add_subplot(132)
      nx.draw_networkx_nodes(
          barbell, pos, node_color=colors, alpha=alpha
      )
      # with more alpha elements than nodes
      alpha.append(1)
      fig.add_subplot(133)
      nx.draw_networkx_nodes(barbell, pos, alpha=alpha)
  
imports: import itertools
  import os
  import warnings
  import pytest
  import networkx
label_desc: Use image node_id 26 for calling a global function with example usage: test_alpha_iter() without return types