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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 save(self, filename):
 """Save the configuration to a file"""

        filename = pathlib.Path(filename)
        out = []
        keys = sorted(list(self.keys()))
        for key in keys:
            out.append("[{}]".format(key))
            section = self[key]
            ikeys = list(section.keys())
            ikeys.sort()
            for ikey in ikeys:
                var, val = keyval_typ2str(ikey, section[ikey])
                out.append("{} = {}".format(var, val))
            out.append("")

        with filename.open("w") as f:
            for i in range(len(out)):
                # win-like line endings
                out[i] = out[i]+"\n"
            f.writelines(out)