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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 get_channel_comment(self, name=None, group=None, index=None):
 """Gets channel comment. Channel can be specified in two ways: * using the first positional argument *name* * if there are multiple occurrences for this channel then the *group* and *index* arguments can be used to select a specific group. * if there are multiple occurrences for this channel and either the *group* or *index* arguments is None then a warning is issued * using the group number (keyword argument *group*) and the channel number (keyword argument *index*). Use *info* method for group and channel numbers If the *raster* keyword argument is not *None* the output is interpolated accordingly. Parameters name : string name of channel group : int 0-based group index index : int 0-based channel index Returns ------- comment : str found channel comment """

        gp_nr, ch_nr = self._validate_channel_selection(name, group, index)

        grp = self.groups[gp_nr]

        channel = grp.channels[ch_nr]

        return extract_cncomment_xml(channel.comment)