diff --git a/docs/reference/not_negative.md b/docs/reference/not_negative.md
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--- a/docs/reference/not_negative.md
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---------------------
-
-## !-
-
-"not negative"
-
-(Function, Boolean Predicate)
-
-Integer on top of stack is replaced by Boolean value indicating whether
-it is non-negative.
-
-        N !-
-    -----------  N < 0
-       false
-
-       N !-
-    ----------  N >= 0
-       true
-
-
-### Definition
-
-    0 >=
-