var 关键字允许声明多个变量，通过逗号分隔。每个变量有一个有效的标识符（第5章），可选的可以有一个值分配，跟在赋值操作符 = 之后。变量也可以有一个显式的类型标记。
The var keyword allows declaring multiple variables, separated by comma ,. Each variable has a valid identifier (5) and optionally a value assignment following the assignment operator =. Variables can also have an explicit type-hint.
var a; // declare local a
var b:Int; // declare variable b of type Int
// declare variable c, initialized to value 1
var c = 1;
// declare variable d and variable e
// initialized to value 2
var d,e = 2;局部变量的作用于行为在块（第5.1节）中描述。
The scoping behavior of local variables is described in Blocks (Section 5.1).