Fixed bug where 5p would be 3p, 3p would be 5p. It was an issue of
removing the sorted keys. Before it worked ok because I added
intron_a5p, intron_b3p. But now that it was intron_5p, intron_3p, I
could not sort it like that. Instead I created function to get the exon
and intron keys.
added a whitespace...??
init commit: filter spliced genes.