code: def suite():
      attribute_suite = (
          unittest.defaultTestLoader.loadTestsFromTestCase(
              AttributeTests
          )
      )
      attribute_combination_suite = (
          unittest.defaultTestLoader.loadTestsFromTestCase(
              AttributeCombinationTests
          )
      )
      unicode_attributes_suite = (
          unittest.defaultTestLoader.loadTestsFromTestCase(
              UnicodeAttributeTests
          )
      )
      return unittest.TestSuite(
          [
              attribute_suite,
              attribute_combination_suite,
              unicode_attributes_suite,
          ]
      )
  
imports: import unittest
  from igraph import Graph
label_desc: Use image node_id 1 for calling a global function with example usage: suite() and returns: unittest