+Make sure not to use a _WARN_ (or higher) log level when the condition
+leading to the logging statement can occur under normal circumstances.
+For example, a public function to get some object or property from an
+object by name or key that fails to find the value is not a warning: the
+user could legitimately use this function to check if the name/key
+exists in the object. In this case, use the _VERBOSE_ level (or do not
+log at all). If a numeric index is out of bounds, however, this
+qualifies for a _WARN_ level: such API functions have documented
+preconditions that the index must be in bounds (the user can always
+check with a count or size function).
+