package definition: unbound variable ungexp

[Reza Alizadeh Majd]

Hello Guix, 

I want to create a plain file during package build and copy it to output. 
but using following definition, I receive error on during package installation:

--- CODE: 
-------------------------------------------------------------------------------------
(add-after 'install 'register-plugin
               (lambda* (#:key outputs #:allow-other-keys)
                  (let* ((out     (assoc-ref outputs "out"))
                             (regpath (string-append out 
"/etc/px/accounts/plugins"))
                             (plugin-data (string-append "plugin:\n"
                                                                                
        "   name: " ,name "\n"
                                                                                
        "   version: " ,version "\n"
                                                                                
        "   type: python\n")))

                     (install-file #$(plain-file "test-plugin.yaml" 
plugin-data) regpath))))
--------------------------------------------------------------------------------------------------

and error that I received during package build: 

--- ERROR: 
------------------------------------------------------------------------------------
starting phase `register-plugin'
Backtrace:
           8 (primitive-load "/gnu/store/fpj6577yfiiz40ci39bw8zzycsy…")
In ice-9/eval.scm:
   191:35  7 (_ #f)
In srfi/srfi-1.scm:
   863:16  6 (every1 #<procedure 531a20 at /gnu/store/4r04fsfcryy5h…> …)
In 
/gnu/store/4r04fsfcryy5h4v2h3g6lzlibafmmdjm-module-import/guix/build/gnu-build-system.scm:
   799:28  5 (_ _)
In ice-9/eval.scm:
    619:8  4 (_ #(#(#(#(#(#(#(#<directory (guile-…>) …) …) …) …) …) …))
    159:9  3 (_ #(#(#(#(#(#(#(#<directory (guile-…>) …) …) …) …) …) …))
   182:19  2 (proc #(#(#(#(#(#(#(#<directory (gui…>) …) …) …) …) …) …))
   142:16  1 (compile-top-call _ (7 . ungexp) ((10 (13 15 7 . #) # …)))
In unknown file:
           0 (%resolve-variable (7 . ungexp) #<directory (guile-user…>)

ERROR: In procedure %resolve-variable:
Unbound variable: ungexp
--------------------------------------------------------------------------------------------------

does any one knows which package do I have to add in order to solve this issue? 


Best, 
Reza