- FYI : https://www.cisco.com/c/en/us/support/docs/field-notices/725/fn72500.html
-- ' A nun once asked a penguin ' do you think the earth is flat ? ; the penguin replied :
Madam, it all depends , in Riemann geometries the earth can be perfectly flat! The nun thanked him , he tripped and fell forward : the poor animal had forgotten that he might be living in a Riemann geometry too!