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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 _file_dict(self, fn_):
        '''
        Take a path and return the contents of the file as a string
        '''
        if not os.path.isfile(fn_):
            err = 'The referenced file, {0} is not available.'.format(fn_)
            sys.stderr.write(err + '\n')
            sys.exit(42)
        with salt.utils.files.fopen(fn_, 'r') as fp_:
            data = fp_.read()
        return {fn_: data}