Read Sourcecode Elisp 'simple.el.gz' 'next line'

#How to find file 'simple.el.gz'? Reading Elisp inside emacs, evoking M-h k, then inputing "Ctrl-n" in minibuffer.
Go to `simple.el' and click RET. There you go.

#Notes

##hard-newlines vs. soft-newlines? check this site out for detals.

##car?cdr? these are opretion working on CONs cells.

car (short for "Contents of the Address part of Register number")
cdr ("Contents of the Decrement part of Register number")

For your better understanding:
(car (cons x y)) evaluates to x, and (cdr (cons x y)) evaluates to y.

#Still dont know...

##abbrev-mode (let ((abbrev-mode nil)) (end-of-line) (insert (if use-hard-newlines hard-newline "\n"))) is abbrev-mode a global variable?
If abbrev-mode is a local variable, why didn't it be used in let expression?

##condition-case (condition-case err (line-move arg nil nil try-vscroll) ((beginning-of-buffer end-of-buffer) (signal (car err) (cdr err)))) After reading the documentation(evoke by M-h f),I still feel confused.

##what if arg is set greater than 1. Scenario:C-u 3 RET C-n
what is the "execute path" in the code?I just can't work it out.