Returns a set number (i) of bytes from self.data.

def __read(self, i: int) -> bytes:
        """Returns a set number (i) of bytes from self.data."""
        b = self.data[self.idx: self.idx + i]
        self.idx += i
        if len(b) != i:
            raise bencodepy.DecodingError(
                "Incorrect byte length returned between indexes of {0} and {1}. Possible unexpected End of File."
                    .format(str(self.idx), str(self.idx - i)))
        return b