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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 one(self, filetype, **kwargs):
        ''' Returns random one of the given type of file

        Parameters
        ----------
        filetype : str
            File type parameter.

        as_url: bool
            Boolean to return SAS urls

        refine: str
            Regular expression string to filter the list of files by
            before random selection

        Returns
        -------
        one : str
            Random file selected from the expanded list of full paths on disk.

        '''
        expanded_files = self.expand(filetype, **kwargs)
        isany = self.any(filetype, **kwargs)
        return choice(expanded_files) if isany else None