code: def test_is_acyclic(self):
      g = Graph.Tree(121, 3, mode="out")
      self.assertTrue(g.is_acyclic())
  
      g = Graph()
      self.assertTrue(g.is_acyclic())
  
      g = Graph.Ring(5)
      self.assertFalse(g.is_acyclic())
  
file_path: python-igraph/tests/test_cycles.py
imports: import random
  import unittest
  from igraph import Graph
label_desc: Use image node_id 2 for calling the CycleTests obj's underlying member method code with example usage: obj.test_is_acyclic() without return types