Hi, I'm putting my own tool into Galaxy. Suppose I have an command line option that is designated by a switch. Such as $executable.py -a option input output The "-a option" is an optional argument. I want to make sure when the option is not given, "-a option" is entirely taken out. I tried Cheetah script like this (this fails): <command interpreter="python">executable #if $option != None -a $option #end if $input $output</command> This $option is suppose to be an optional tabular file and is written within <param> as: <param name="option" type="data" format="tabular" label="XXX" optional="true"/> Somehow "-a None" is always printed (as seen from the server print-to-screen). But I thought I checked explicitly for it to be anything but None. Then I realized that type($option) <class 'galaxy.tools.DatasetFilenameWrapper'>. So I coerced both that and NoneType into string prior to checking for equality. Is this the proper way to do it? Timothy