So, the first thing I need to do is, if it's the first line of this file,
which starts with an arrow, we want to ignore that.
That just has information that we don't really care about.
So I'm going to say, if the first character in the line is not
the arrow, than it must be a line containing bases.
So in this case I'm going to add it onto our genome string.
So I'm going to say, genome += line.rstrip.
And what rstrip does is it removes any
trailing white space from the ends of the string.
So in this case it will trim off the new line at the end.
If there are spaces, tabs, any other white space,
it will also trim those off as well.