code: def add(self, data_bytes):
          '''Feed ASCII string or bytes to the signature function'''
          try:
              if isinstance(data_bytes, basestring):  # Python 2.7 compatibility
                  data_bytes = map(ord, data_bytes)
          except NameError:
              if isinstance(data_bytes, str):  # This branch will be taken on Python 3
                  data_bytes = map(ord, data_bytes)
  
          for b in data_bytes:
              self._crc ^= (b << 56) & Signature.MASK64
              for _ in range(8):
                  if self._crc & (1 << 63):
                      self._crc = ((self._crc << 1) & Signature.MASK64) ^ Signature.POLY
                  else:
                      self._crc <<= f add(self, data_bytes):
          '''Feed ASCII string or bytes to the signature function'''
          try:
              if isinstance(data_bytes, basestring):  # Python 2.7 compatibility
                  data_bytes = map(ord, data_bytes)
          except NameError:
              if isinstance(data_bytes, str):  # This branch will be taken on Python 3
                  data_bytes = map(ord, data_bytes)
  
          for b in data_bytes:
              self._crc ^= (b << 56) & Signature.MASK64
              for _ in range(8):
                  if self._crc & (1 << 63):
                      self._crc = ((self._crc << 1) & Signature.MASK64) ^ Signature.POLY
                  else:
                      self._crc <<= 1
docs: Feed ASCII string or bytes to the signature function