Golang provide own enumerate method which is easy and very powerful. I will show you enumerate with in a sec. When i code enumerate in java, believe me i don't understand why it's used? So i never play from this card at that time, but recently when i start learning go. Now i used where it's used and why? Enumerate basically a counting method.
If you remember adding color layer then you familiar from this code. First i create my own type called weekend then used this type.
Things that confuse you Sunday Weekend = iota & Monday without value. Before we start Iota-generator first we understand monday without type or value
c = 1 // c : 1
d // d : 1
This is only possible for consts. If you have 2 const and both have same type and same value then you omit next type or value. That's why program execute without error. Result of this problem is "11".
Now time to dive in iota generator. When you assign any const iota which means const initialize with 0, but after iota value increment. That's little different from previous code. As you know enumerate counts. That's iota do for us. Now you know the output of above code.