Hi, I am a new galaxy developer playing with writing my first plugins In my plugin xml configaration file: I want to be able to increase the value of one parameter based on another using <command interpreter="python"> #if $rows.option =="header_ignore" #set $data_start = $rows.ignore + 1 but I get: unsupported operand type(s) for +: 'InputValueWrapper' and 'int' A hack workaround I found was: #set $data_start = int(str($rows.ignore)) + 1 I just wondered if there was a cleaner way to get the integer value from a InputValueWrapper object. Which is set to integer by: <param name="ignore" size="4" type="integer" value="1" .... If documentation exist somwere please send me an RTFM link. (I didn't find it in https://wiki.galaxyproject.org/Admin/Tools/ToolConfigSyntax) Thanks in advance Christian Brenninkmeijer University of Manchester Ps. If you want to see exactly what I am playing with see https://github.com/Christian-B/galaxy_tools/tree/master/summary (Note that is subject to change as I learn)