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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 plot_dict(self, flags, label='key', known='x', **kwargs):
 """Plot a `~gwpy.segments.DataQualityDict` onto these axes Parameters flags : `~gwpy.segments.DataQualityDict` data-quality dict to display label : `str`, optional labelling system to use, or fixed label for all `DataQualityFlags`. Special values include - ``'key'``: use the key of the `DataQualityDict`, - ``'name'``: use the :attr:`~DataQualityFlag.name` of the `DataQualityFlag` If anything else, that fixed label will be used for all lines. known : `str`, `dict`, `None`, default: '/' display `known` segments with the given hatching, or give a dict of keyword arguments to pass to :meth:`~SegmentAxes.plot_segmentlist`, or `None` to hide. **kwargs any other keyword arguments acceptable for `~matplotlib.patches.Rectangle` Returns ------- collection : `~matplotlib.patches.PatchCollection` list of `~matplotlib.patches.Rectangle` patches """

        out = []
        for lab, flag in flags.items():
            if label.lower() == 'name':
                lab = flag.name
            elif label.lower() != 'key':
                lab = label
            out.append(self.plot_flag(flag, label=to_string(lab), known=known,
                                      **kwargs))
        return out