pydata/pandas — comment on commit 14a58b6a5ff13f9a21451e8b8cd2d9bfcb839f8e
File: pandas/tests/test_frame.py line 3382
By adamklein:

Yep, officially the API is:
def shift(self, periods, offset=None, **kwds):
I've been going with offset (not freq) everywhere, to keep consistent with prior naming choices. Any issues here?