-;;; binding in ENV, bind the variable to the value in ENV, and then
-;;; evaluate the next binding form. Once all binding forms have been
-;;; handled, END-ACTION is funcalled.
+;;; binding in ENV, generate an augmented environment with a binding
+;;; of the variable to the value in ENV, and then evaluate the next
+;;; binding form. Once all binding forms have been handled, END-ACTION
+;;; is funcalled with the final environment.