go channel 语法

Question

如题

各位大侠，请问下面代码中两个values后面那个冒号的位置为什么一前一后啊？

Answer 1

a := []int{1, 2, 3, 4}

a[2:]  // same as a[2 : len(a)] ==> []int{3, 4}
a[:3]  // same as a[0 : 3]      ==> []int{1, 2, 3}
a[:]   // same as a[0 : len(a)] ==> []int{1, 2, 3, 4}

https://golang.org/ref/spec#Slice_expressions

Answer 2

slice切片，没用过python吗？