I am trying to merge a list of tuples, say:
 `test = [('X','X'),('O','O'),('X','X')]`
into
 `test_merge = ['XX','OO','XX']`

And I read from another person that he/she uses:

> 
> map(''.join, test)  
> 
>  and got:  
> 
>  ['XX', 'OO', 'XX']
> 
> 
> 

So I thought about trying a different way:

> 
> ''.join(map(str, test))  
> 
>  and got:  
> 
>  "('X', 'X')('O', 'O')('X', 'X')"
> 
> 
> 

I understand that `''.join` cannot be used without the `test` being a list of string. But, with the same map() and join(), how come `map(''join, test)` succeeds in merging the values in a tuple? Many thanks!