Node:insert-buffer code, Next:insert-buffer interactive, Previous:insert-buffer, Up:insert-buffer
insert-bufferHere is the code:
(defun insert-buffer (buffer)
  "Insert after point the contents of BUFFER.
Puts mark after the inserted text.
BUFFER may be a buffer or a buffer name."
  (interactive "*bInsert buffer: ")
  (or (bufferp buffer)
      (setq buffer (get-buffer buffer)))
  (let (start end newmark)
    (save-excursion
      (save-excursion
        (set-buffer buffer)
        (setq start (point-min) end (point-max)))
      (insert-buffer-substring buffer start end)
      (setq newmark (point)))
    (push-mark newmark)))
As with other function definitions, you can use a template to see an outline of the function:
(defun insert-buffer (buffer) "documentation..." (interactive "*bInsert buffer: ") body...)