CSNote

1st

1. 变量类型必须有，且不可改变，在运行前verify
   1. 
2. A func is called a method
   1. define func --> public staic
   2. func's parameters and return value must declared type
   3. Only one return val

2nd

1. 没有main的method可以在有main的method里被调用
   1.