Generated by `pyupgrade --py3-plus --keep-percent-format` on all our Python code except `zthumbor` and `zulip-ec2-configure-interfaces`, followed by manual indentation fixes. Signed-off-by: Anders Kaseorg <anders@zulipchat.com>
Signed-off-by: Anders Kaseorg <andersk@mit.edu>
Fixes #38.