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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 _get_abs_filepath(self, ifile):
 """ validate src or dst file path with self.config_file """

        assert ifile is not None
        ifile = ifile[7:] if ifile.startswith('file://') else ifile
        if ifile[0] != '/':
            basedir = os.path.abspath(os.path.dirname(self.config_file))
            ifile = os.path.join(basedir, ifile)
        return 'file://' + ifile