old_contents: import ast
  import builtins
  
  from .operator import Operator
  
  
  class OutOfNoWhereException(Exception):
      pass
  
  setattr(builtins, OutOfNoWhereException.__name__, OutOfNoWhereException)
  
  
  class ExceptionReplacer(Operator):
  
      """An operator that modifies exception handlers."""
  
      def visit_ExceptHandler(self, node):  # noqa
          return self.visit_mutation_site(node)
  
      def mutate(self, node, _):
          """Modify the exception handler with another exception type."""
          except_id = OutOfNoWhereException.__name__
          except_type = ast.Name(id=except_id, ctx=ast.Load())
          new_node = ast.ExceptHandler(type=except_type, name=node.name,
                                       body=node.body)
          return new_node
  
new_contents: import ast
  import builtins
  
  from .operator import Operator
  
  
  class CosmicRayTestingException(Exception):
      pass
  
  setattr(builtins, CosmicRayTestingException.__name__, CosmicRayTestingException)
  
  
  class ExceptionReplacer(Operator):
  
      """An operator that modifies exception handlers."""
  
      def visit_ExceptHandler(self, node):  # noqa
          return self.visit_mutation_site(node)
  
      def mutate(self, node, _):
          """Modify the exception handler with another exception type."""
          except_id = CosmicRayTestingException.__name__
          except_type = ast.Name(id=except_id, ctx=ast.Load())
          new_node = ast.ExceptHandler(type=except_type, name=node.name,
                                       body=node.body)
          return new_node
  
subject: Change exception name to CosmicRayTestingException