Takes a chunk of a document and feeds it through all of the relevant
        charset probers.

        After calling ``feed``, you can check the value of the ``done``
        attribute to see if you need to continue feeding the
        ``UniversalDetector`` more data, or if it has made a prediction
        (in the ``result`` attribute).

        .. note::
           You should always call ``close`` when you're done feeding in your
           document if ``done`` is not already ``True``.

def feed(self, byte_str):
        """
        Takes a chunk of a document and feeds it through all of the relevant
        charset probers.

        After calling ``feed``, you can check the value of the ``done``
        attribute to see if you need to continue feeding the
        ``UniversalDetector`` more data, or if it has made a prediction
        (in the ``result`` attribute).

        .. note::
           You should always call ``close`` when you're done feeding in your
           document if ``done`` is not already ``True``.
        """
        if self.done:
            return

        if not len(byte_str):
            return

        if not isinstance(byte_str, bytearray):
            byte_str = bytearray(byte_str)

        # First check for known BOMs, since these are guaranteed to be correct
        if not self._got_data:
            # If the data starts with BOM, we know it is UTF
            if byte_str.startswith(codecs.BOM_UTF8):
                # EF BB BF  UTF-8 with BOM
                self.result = {'encoding': "UTF-8-SIG",
                               'confidence': 1.0,
                               'language': ''}
            elif byte_str.startswith((codecs.BOM_UTF32_LE,
                                      codecs.BOM_UTF32_BE)):
                # FF FE 00 00  UTF-32, little-endian BOM
                # 00 00 FE FF  UTF-32, big-endian BOM
                self.result = {'encoding': "UTF-32",
                               'confidence': 1.0,
                               'language': ''}
            elif byte_str.startswith(b'\xFE\xFF\x00\x00'):
                # FE FF 00 00  UCS-4, unusual octet order BOM (3412)
                self.result = {'encoding': "X-ISO-10646-UCS-4-3412",
                               'confidence': 1.0,
                               'language': ''}
            elif byte_str.startswith(b'\x00\x00\xFF\xFE'):
                # 00 00 FF FE  UCS-4, unusual octet order BOM (2143)
                self.result = {'encoding': "X-ISO-10646-UCS-4-2143",
                               'confidence': 1.0,
                               'language': ''}
            elif byte_str.startswith((codecs.BOM_LE, codecs.BOM_BE)):
                # FF FE  UTF-16, little endian BOM
                # FE FF  UTF-16, big endian BOM
                self.result = {'encoding': "UTF-16",
                               'confidence': 1.0,
                               'language': ''}

            self._got_data = True
            if self.result['encoding'] is not None:
                self.done = True
                return

        # If none of those matched and we've only see ASCII so far, check
        # for high bytes and escape sequences
        if self._input_state == InputState.PURE_ASCII:
            if self.HIGH_BYTE_DETECTOR.search(byte_str):
                self._input_state = InputState.HIGH_BYTE
            elif self._input_state == InputState.PURE_ASCII and \
                    self.ESC_DETECTOR.search(self._last_char + byte_str):
                self._input_state = InputState.ESC_ASCII

        self._last_char = byte_str[-1:]

        # If we've seen escape sequences, use the EscCharSetProber, which
        # uses a simple state machine to check for known escape sequences in
        # HZ and ISO-2022 encodings, since those are the only encodings that
        # use such sequences.
        if self._input_state == InputState.ESC_ASCII:
            if not self._esc_charset_prober:
                self._esc_charset_prober = EscCharSetProber(self.lang_filter)
            if self._esc_charset_prober.feed(byte_str) == ProbingState.FOUND_IT:
                self.result = {'encoding':
                               self._esc_charset_prober.charset_name,
                               'confidence':
                               self._esc_charset_prober.get_confidence(),
                               'language':
                               self._esc_charset_prober.language}
                self.done = True
        # If we've seen high bytes (i.e., those with values greater than 127),
        # we need to do more complicated checks using all our multi-byte and
        # single-byte probers that are left.  The single-byte probers
        # use character bigram distributions to determine the encoding, whereas
        # the multi-byte probers use a combination of character unigram and
        # bigram distributions.
        elif self._input_state == InputState.HIGH_BYTE:
            if not self._charset_probers:
                self._charset_probers = [MBCSGroupProber(self.lang_filter)]
                # If we're checking non-CJK encodings, use single-byte prober
                if self.lang_filter & LanguageFilter.NON_CJK:
                    self._charset_probers.append(SBCSGroupProber())
                self._charset_probers.append(Latin1Prober())
            for prober in self._charset_probers:
                if prober.feed(byte_str) == ProbingState.FOUND_IT:
                    self.result = {'encoding': prober.charset_name,
                                   'confidence': prober.get_confidence(),
                                   'language': prober.language}
                    self.done = True
                    break
            if self.WIN_BYTE_DETECTOR.search(byte_str):
                self._has_win_bytes = True