code: def fromOctetString(cls, value, internalFormat=False, prepend=None, padding=0):
          
          value = SizedInteger(integer.from_bytes(value) >> padding).setBitLength(len(value) * 8 - padding)
  
          if prepend is not None:
              value = SizedInteger(
                  (SizedInteger(prepend) << len(value)) | value
              ).setBitLength(len(prepend) + len(value))
  
          if not internalFormat:
              value = cls(value)
  
          return value
docs: Create a |ASN.1| object initialized from a string.
  
          Parameters
          ----------
          value: :class:`str` (Py2) or :class:`bytes` (Py3)
              Text string like '\\\\x01\\\\xff' (Py2) or b'\\\\x01\\\\xff' (Py3)