Declare func name(parameter-list) return-list {...}
Parameter list type can be declared only once if types are the same
func test(a string, b string, c string)
func test(a,b,c string)
func test(a,b,c string,d,e,f int)
Return list can be named as well, don't need "return" statement if variable name is the same, called bare return。bare return is hard to under
If return list type are the same, can be declared only once
Can declare parameter name as _ to indicate the parameter is unused (But I'm not sure when should use it)
Go doesn't support default parameter value
Go doesn't support specify parameter value by name
