>>> s._job
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/path/to/my/virtualenv/site-packages/schedule/__init__.py", line 284, in __repr__
    args = [repr(x) if is_repr(x) else str(x) for x in self.job_func.args]
AttributeError: 'NoneType' object has no attribute 'args'

Line 284 (and similarly line 285 for kwargs) assumes self.job_func is not None (and has the "args" attribute). I think it needs to use logic similar to line 264 (and line 265, respectively for kwargs).

It may be helpful to extract line 264 to a reusable property:

@property
def _job_func_args(self):
    return () if self.job_func is None else self.job_func.args

I can draft a PR if that would be helpful.

For context, I am using schedule as a schedule-builder interface, (i.e. just Job definitions without do).