[basex-talk] xquery:eval and bindings argument

I apologize in advance, because I know the answer will be simple (but I couldn't find an example and have tried all sorts of options). I am trying to run xquery:eval passing in a string to evaluate and a map of bindings.  Everything I try I get an 'Undefined variable' error. Here is a simple example I tried in the BaseX Gui.  let $a := 3let $string := "$a + 1"returnxquery:eval($string, map{"a" : $a} This is just one attempt, but there were many others. Again, I know this is going to be a simple mistake I'm making, so apologies to the community in advance.

Thanks, Buddy