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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def _highlight_lines(self, tokensource):
 """ Highlighted the lines specified in the `hl_lines` option by post-processing the token stream coming from `_format_lines`. """

        hls = self.hl_lines

        for i, (t, value) in enumerate(tokensource):
            if t != 1:
                yield t, value
            if i + 1 in hls:  # i + 1 because Python indexes start at 0
                if self.noclasses:
                    style = ''
                    if self.style.highlight_color is not None:
                        style = (' style="background-color: %s"' %
                                 (self.style.highlight_color,))
                    yield 1, '<span%s>%s</span>' % (style, value)
                else:
                    yield 1, '<span class="hll">%s</span>' % value
            else:
                yield 1, value