Redundant of removed.

Karsten7 · kay-kim · commit efff73d4c1e5 · 2018-10-04T13:30:56.000-04:00
diff --git a/source/reference/operator/aggregation/toBool.txt b/source/reference/operator/aggregation/toBool.txt
@@ -23,7 +23,7 @@ Definition
 
    .. versionadded:: 4.0
 
-   Converts a value of to a boolean.
+   Converts a value to a boolean.
 
    :expression:`$toBool` has the following syntax:
 
