Return true if this is a binary file.

def is_binary(self):
        """Return true if this is a binary file."""
        with open(self.path, 'rb') as fin:
            CHUNKSIZE = 1024
            while 1:
                chunk = fin.read(CHUNKSIZE)
                if b'\0' in chunk:
                    return True
                if len(chunk) < CHUNKSIZE:
                    break
        return False