code: def _iupac_ambiguous_equal(ambig_base, unambig_base):
      
      iupac_translation = {
          'A': 'A',
          'C': 'C',
          'G': 'G',
          'T': 'T',
          'U': 'U',
          'R': 'AG',
          'Y': 'CT',
          'S': 'GC',
          'W': 'AT',
          'K': 'GT',
          'M': 'AC',
          'B': 'CGT',
          'D': 'AGT',
          'H': 'ACT',
          'V': 'ACG',
          'N': 'ACGT',
          '-': '-'
      }
      for i in (ambig_base, unambig_base):
          if not len(i) == 1:
              raise ValueError("only one base may be passed.")
  
      return unambig_base.upper() in iupac_translation[ambig_base.upper()]
docs: Tests two bases for equality, accounting for IUPAC ambiguous DNA
  
      ambiguous base may be IUPAC ambiguous, unambiguous must be one of ACGT