code: def convert_exception(from_exception, to_exception, *to_args, **to_kw):
      
      def wrapper(fn):
  
          def fn_new(*args, **kw):
              try:
                  return fn(*args, **kw)
              except from_exception:
                  new_exception = to_exception(*to_args, **to_kw)
                  traceback = sys.exc_info()[2]
                  if PY3:
                      value = new_exception
                  else:
                      value = None
                  reraise(new_exception, value, traceback)
  
          fn_new.__doc__ = fn.__doc__
          return fn_new
  
      return wrapper
docs: Decorator: Catch exception ``from_exception`` and instead raise ``to_exception(*to_args, **to_kw)``.
  
      Useful when modules you're using in a method throw their own errors that you want to
      convert to your own exceptions that you handle higher in the stack.
  
      Example: ::
  
          class FooError(Exception):
              pass
  
          class BarError(Exception):
              def __init__(self, message):
                  self.message = message
  
          @convert_exception(FooError, BarError, message='bar')
          def throw_foo():
              raise FooError('foo')
  
          try:
              throw_foo()
          except BarError as e:
              assert e.message == 'bar'