Debug message added.
More debug messages.
Fixed typo.
Simpler docstring wording.
Rationale for the robust_format function added.
Added error message for users (with ValueError, like when using a wrong format like '{:d}'.format(3.14)).
Removed meaningless format test.
Fixed typoe.
Test updated with new notation for a non-zero error rounded to 0.
Fixed stupid bug.
Fixed test.