Suppose I have the following string:

s = "iPhone" ' string length is 6

I want to modify the above string variable such that
the string length is 20, AND, the string is centered or
padded with spaces.

The result should look like:

s = " iPhone " ' string length is 20

Does that make sense? I just want to transform a
string variable so it is padded with space characters
and it appears (somewhat) centered. I prefer
a general solution for situations where I want to
center the string within a string length of N characters.

Thanks!