+__Smart shell__
+
+* Put anything to terminal, the app will try to eval and display result as a python interactive shell.
+ * `142857*2` or `101**3` like a calculator.
+ * Even `cal` will show the calendar for current month.
+ * Put `order_rainbow('anything')` or `random_rainbow('wahahaha')` will make more fun :)
+
+__Screening Commands__
+
+* `h` will show the help.
+
+* `c` will clear the screen.
+
+* `q` will quit.
+