code: def seq_md5(seq, normalize=True):
      
      seq = normalize_sequence(seq) if normalize else seq
      bseq = seq.encode("ascii")
      return hashlib.md5(bseq).hexdigest()
docs: returns unicode md5 as hex digest for sequence `seq`.
  
      >>> seq_md5('')
      'd41d8cd98f00b204e9800998ecf8427e'
  
      >>> seq_md5('ACGT')
      'f1f8f4bf413b16ad135722aa4591043e'
  
      >>> seq_md5('ACGT*')
      'f1f8f4bf413b16ad135722aa4591043e'
  
      >>> seq_md5(' A C G T ')
      'f1f8f4bf413b16ad135722aa4591043e'
  
      >>> seq_md5('acgt')
      'f1f8f4bf413b16ad135722aa4591043e'
  
      >>> seq_md5('acgt', normalize=False)
      'db516c3913e179338b162b2476d1c23f'