ambrevar/shell: Add toggle-clesh-readtable.

.local/share/common-lisp/source/ambrevar/shell.lisp

@@ -337,6 +337,12 @@ If PARENT-DIRECTORY is not a parent of PATH, return PATH."
       (named-readtables:in-readtable :standard)
       (named-readtables:in-readtable :interpol-syntax)))
 
+(export-always 'toggle-clesh-readtable)
+(defun toggle-clesh-readtable ()
+  (if (eq *readtable* (named-readtables:find-readtable 'clesh:syntax))
+      (named-readtables:in-readtable :standard)
+      (named-readtables:in-readtable clesh:syntax)))
+
 (export-always 'move-file)
 (defun move-file (source destination)
   "`rename-file' does not work cross-device, in particular it does not work on