code: function(forms) {
      var opName = sl.valueOf(forms[0]);
      if (forms.length < 2)  {
        forms.error("missing argument for unary operator: " + opName);
      }
  
      this.transpileSubExpressions(forms)
      var generated = sl.generated();
      var postPrefix = "post";
      if(opName.indexOf(postPrefix) === 0) {
        generated.push([sl.valueOf(forms[1]),opName.substring(postPrefix.length)]);
      }
      else {
        generated.push([forms[0], sl.valueOf(forms[1])]);
      }
      generated.callable = false;
      return generated;
  }
docs: Handle a unary operator e.g. i++, --i, etc. We're using a convention that prefix unary such as --i comes through as "--", but postfix unary like i-- comes through as "post--"