Upd help functions

diff --git a/help/help_functions.md b/help/help_functions.md
index a14f2b7321d35f8bc1f9ae5fb6d991774ac6b24b..52a7a2baab149a086b73baee6174779d0f71dfcd 100644 (file)
--- a/help/help_functions.md
+++ b/help/help_functions.md
@@ -214,7 +214,7 @@ Syntax:
 
        filter(<operator> <value>)
 
-Returns an integer or float value depending on the series data type.
+Returns an integer, float or string value depending on the series data type.
 
 Filter is used to filter the result by values.
 
@@ -225,6 +225,9 @@ Example:
 
     # Select all positive values from 'series-001'
     select filter(> 0) from 'series-001'
+    
+    # Select all values containing 'error' and not 'unavailable
+    select filter(~'error') => filter(!~'unavailable') from 'some-log-series'
 
 
 first