(defun read-warc-record (file offset len)
  (with-open-file (in file :direction :input :element-type 'unsigned-byte)
    (when in
      (let ((arr (make-array (+ offset len))))
        (print arr)
        (read-sequence arr in :start offset :end (+ offset len))
        (map 'string #'code-char (remove-if #'(lambda (x) (null x)) arr))))))