code: def assert_valid_vertex_coloring(graph, coloring):
      assert min(coloring) == 0
      for edge in graph.es:
          source, target = edge.tuple
          assert (
              source == target or coloring[source] != coloring[target]
          )
  
imports: import unittest
  from igraph import Graph
label_desc: Use image node_id 1 for calling a global function with example usage: assert_valid_vertex_coloring(graph, coloring) without return types