text: from django.forms import Field
  from django.test import SimpleTestCase
  
  
  class BasicFieldsTests(SimpleTestCase):
  
      def test_field_sets_widget_is_required(self):
          self.assertTrue(Field(required=True).widget.is_required)
          self.assertFalse(Field(required=False).widget.is_required)
  
      def test_cooperative_multiple_inheritance(self):
          class A(object):
              def __init__(self):
                  self.class_a_var = True
                  super(A, self).__init__()
  
          class ComplexField(Field, A):
              def __init__(self):
                  super(ComplexField, self).__init__()
  
          f = ComplexField()
          self.assertTrue(f.class_a_var)
  