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ValueError

$ myscript --help
ValueError: unsupported format character ')' (0x29) at index ...

ValueError: incomplete format

Reason: One or more argument help-strings contain the character '%'
   Example: help='Percent threshold (default: 80 %)'

Solution: escape the % character with another % to have a double %%
   Example:
help='Percent threshold (default: 80 %%)'