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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 fade_in(self, segment, duration, fade_type="linear"):
 """Adds a fade in to a segment in the composition :param segment: Segment to fade in to :type segment: :py:class:`radiotool.composer.Segment` :param duration: Duration of fade-in (in seconds) :type duration: float :returns: The fade that has been added to the composition :rtype: :py:class:`Fade` """

        f = Fade(segment.track, segment.comp_location_in_seconds,
                 duration, 0.0, 1.0, fade_type=fade_type)
        self.add_dynamic(f)
        return f