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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 dump_df(self, df, version=None, tags=None, ext=None, **kwargs):
 """Dumps an instance of this dataset into a file. Parameters df : pandas.DataFrame The dataframe to dump to file. version: str, optional The version of the instance of this dataset. tags : list of str, optional The tags associated with the given instance of this dataset. ext : str, optional The file extension to use. If not given, the default extension is used. **kwargs : extra keyword arguments, optional Extra keyword arguments are forwarded to the serialization method of the SerializationFormat object corresponding to the extension used. """

        if ext is None:
            ext = self.default_ext
        fpath = self.fpath(version=version, tags=tags, ext=ext)
        fmt = SerializationFormat.by_name(ext)
        fmt.serialize(df, fpath, **kwargs)