def _get_base_alphabet(alphabet):
 a = alphabet
 while isinstance(a, AlphabetEncoder):
  a = a.alphabet
 assert isinstance(a, Alphabet), ('Invalid alphabet found, %s' % repr(a))
 return a

def _get_base_alphabet ( alphabet ) : a = alphabet while isinstance ( a , AlphabetEncoder ) : a = a . alphabet assert isinstance ( a , Alphabet ) , ( 'Invalid alphabet found, %s' % repr ( a ) ) return a
returns the non-gapped non-stop-codon alphabet object .