# The Triplets alphabet:

Triplets(nucleotides)

The Triplets alphabet is used for triplets of DNA or RNA data.
It is like the Codons alphabet, with the difference that:

 * stop codons not excluded from a Triplets alphabet.
 * the genetic code is not known by a Triplets alphabet.

Therefore, the Triplets alphabet cannot be used in models that
estimate dN/dS.

The nucleotides argument can be `DNA`, `RNA`, or missing.  If it
is missing, DNA or RNA is guessed based on frequency of
A,T,G,U, and C in the file.

# Examples:

   Triplets
   Triplets(RNA)
   Triplets(DNA)

# See also:

   Codons
