how to concatenate tkinter variable and textvariable in label code example

Example 1: how to make a variable unchangeable in java

class scratch{
	public static void main(String[] args){
		final pi = 3.14;
	}
}

Example 2: python value is unsubscriptable when using [:]

a = 1337
b = [1,3,3,7]
print b[0] # prints 1
print a[0] # raises your exception