Add break and continue useage

Signed-off-by: Lynn <sotii@163.com>
Add more useage about for and while

Signed-off-by: Lynn <sotii@163.com>
Add useage about function

Signed-off-by: Lynn <sotii@163.com>
Recursion

Signed-off-by: Lynn <sotii@163.com>
Add useage about class

Signed-off-by: Lynn <sotii@163.com>
Add useage about exception

Signed-off-by: Lynn <sotii@163.com>
Add useage about future iter rule

Important

Signed-off-by: Lynn <sotii@163.com>