A common thing you need to do with an object list is filter it down to just the ones that have a certain attribute. It's easy enough to write a function to do that, but I always wondered why there's a FilterByAttribute, but not FilterByHasAttribute (or whatever you'd call it).
I end up writing that function every time I start a new project.

Just realised: FilterByAttribute (AllObjects(), "description", null) will find all objects that don't have a description. And the corresponding FilterByNotAttribute() call will find all objects that do have a given attribute. Because it uses Equal() to test, so a null value is the same as not having the attribute.

Maybe this should be in the documentation.
Or even, a little tweak to make the usage slightly more intuitive:

  <function name="FilterByAttribute" parameters="lst, name, value" type="objectlist">
    if (not IsDefined("value")) {
      return (FilterByNotAttribute (lst, name, null))
    }
    l = NewObjectList()
    foreach (o, lst) {
      val = GetAttribute(o, name)
      if (Equal(val, value)) list add (l, o)
    }
    return (l)
  </function>

  <function name="FilterByNotAttribute" parameters="lst, name, value" type="objectlist">
    if (not IsDefined("value")) {
      return (FilterByAttribute (lst, name, null))
    }
    l = NewObjectList()
    foreach (o, lst) {
      val = GetAttribute(o, name)
      if (not Equal(val, value)) list add (l, o)
    }
    return (l)
  </function>

↑ With that little change (if I understand the rules right), the user could call FilterByAttribute (somelist, "someattribute"), omitting the third attribute to get a list of objects which have (or don't have) an attribute regardless of value. I think that's a fairly natural thing for a programmer to assume would be possible, so it would be nice to have it Just Work.

I’ve got no input here but, based on your title, I’d be glad to put that you’re an idiot in the documentation. Haha.

Burn.
They are certainly handy functions. For now it would be nice to see your new functions(these and any others) in a Function.aslx library.

New filter by attribute functions. FilterByNotAttribute() and FilterByAttribute (AllObjects(), "description", null).
Got it!
Yes, those should be in the tutorials!