Parse the SEQRES entries into the object

def parse_seqres(self, pdb):
    """Parse the SEQRES entries into the object"""
    
    seqresre = re.compile("SEQRES")
    
    seqreslines = [line for line in pdb.lines if seqresre.match(line)]
    
    for line in seqreslines:
      chain = line[11]
      resnames = line[19:70].strip()
      self.setdefault(chain, [])
      self[chain] += resnames.split()