At 3.9.0, some rogue commas can cause a hang to occur
# cf/field.py
logger.info(
" After collapse of data:\n"
f" f.shape = {f.shape}\n"
f" f.dtype = {f.dtype}\n",
f"collapse_axes = {collapse_axes}",
) # pragma: no cover
https://github.com/NCAS-CMS/cf-python/blob/v3.9.0/cf/field.py#L9894-L9899
All of the commas in this snippet should be removed.