```common lisp
(cl:in-package #:sicl-boot-phase1)

(defun fill-environment (linkage-environment)
  (declare (ignore linkage-environment))
  nil)
```

Define function LD for loading files.
user
```common lisp
(cl:in-package #:sicl-boot-phase1)

(defun ld (filename environment)
  (format *trace-output* "Loading file ~a~%" filename)
  (finish-output *trace-output*)
  (sicl-extrinsic-environment:load-source-with-environments
   filename (compilation-environment environment) environment))

(defun fill-environment (environment)
  (ld "../../CLOS/ensure-generic-function-using-class-defgenerics.lisp"
      environment))
```
assistant