Printing Tuple!(...)[] using for loop?

[Kirill]

I have a `Tuple!(string, ..., string)[] data` that I would like 
to print out:
`a   b   c`
`1   2   3`
`4   5   6`

     Furthermore, I want to be able to print any N rows and M 
columns of that table. For instance:
         `b   c`
         `2   3`
         or
         `1   2   3`
         `4   5   6`

I am using for loops for that:

         // inside some function(rows, cols):
         immutable startFromRow = ...;
         immutable endWithRow = ...;
         immutable startFromCol = ...;
         immutable endWithCol = ...;
         		
         // print data
         for(size_t i = startFromRow; i < endWithRow; i++) {
         	for(size_t j = startFromCol; j < endWithCol; j++) {
         		writef("%s", data[i][j]);
         	}
         	writef("\n");
         }

And the compiler puts out the following:
`Error: variable 'j' cannot be read at compile time`

I tried `data[i].expand[j]`, but the same error occurs anyway.

I have two questions:
1. How do I print the contents of a Tuple using for loops? Or any 
other method?
2. What am I missing? How does it actually work under the hood?

Thanks in advance. Any help is greatly appreciated.