docs: def pair_hmm_align_unaligned_seqs(seqs, moltype=DNA_cogent, params={}):
      """
          Checks parameters for pairwise alignment, returns alignment.
  
          Code from Greg Caporaso.
      """
  
      seqs = LoadSeqs(data=seqs, moltype=moltype, aligned=False)
      try:
          s1, s2 = seqs.values()
      except ValueError:
          raise ValueError(
              "Pairwise aligning of seqs requires exactly two seqs.")
  
      try:
          gap_open = params['gap_open']
      except KeyError:
          gap_open = 5
      try:
          gap_extend = params['gap_extend']
      except KeyError:
          gap_extend = 2
      try:
          score_matrix = params['score_matrix']
      except KeyError:
          score_matrix = make_dna_scoring_dict(
              match=1, transition=-1, transversion=-1)
  
      return local_pairwise(s1, s2, score_matrix, gap_open, gap_extend)