[expr] [bool]ean negation operator

returns truth (1) if the argument is a falsehood, and falsity (0) of the argument is true

For bitwise "not" use the [~] operator.

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[AMG]: To convert a value to its canonical boolean representation (i.e. 0 or 1), you can use `[[expr {'''!!'''$val}]]`.

[LV] Out of curiosity, why are two ! needed? Doesn't one '''!''' always result in either a 0 or a 1 being returned?

[AMG]: Yes, but using a single '''!''' will also invert the value.  Using an even number of '''!''''s will cause the value to not be inverted.

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!!!!!!
%| [Category Operator] |%
!!!!!!