[BioRuby] Non deprecated way of converting a naseq to fasta?

[Andrew Grimm]

The documentation for Bio::Sequence::Common talks about #to_fasta being
deprecated, in favor of Bio::Sequence #output instead. #output seems to work
for Bio::Sequence objects, but not for Bio::Sequence::NA or
Bio::Sequence::AA objects.

I can happily create a new FastaFormat object instead, but I'm wondering if
I'm doing it the right way.

Also, the wiki is still suggesting using to_fasta in some of its code
samples.

Thanks,

Andrew Grimm