linkify . url http://www.youtube.com/watch?v=5Jt5GEr4AYg. .
url http://www.youtube.com/watch?v=5Jt5GEr4AYg.
. don't touch text in links . [https://example.com](https://example.com) . . don't touch text in autolinks .before github.com
. after line . github.com after .github.com after
. before after lines . before github.com after .before github.com after
. before after lines with blank line . before github.com after .before
after
.