new_contents: from pychecker2.TestSupport import WarningTester
  from pychecker2 import ReturnChecks
  
  class ReturnTestCase(WarningTester):
      def testReturnChecks(self):
          w = ReturnChecks.MixedReturnCheck.mixedReturns
          self.silent('def f(): return\n')
          self.silent('def f(): return 1\n')
          self.silent('def f(x):\n'
                       '  if x:\n'
                       '    return 0\n'
                       '  return 1\n')
          self.warning('def f(x):\n'
                       '  if x:\n'
                       '    return\n'
                       '  return 1\n', 3, w, 'f')
          self.silent('def f(x):\n'
                      '  def g():\n'
                      '    return\n'
                      '  return x + g()\n')
  
  
subject: test mixed returns