Remove string-based make_function and swap out _ast for ast.
Remove string-based make_function and swap out _ast for ast.

harrissoerja/vumi,vishwaprakashmishra/xmatrix,TouK/vumi,vishwaprakashmishra/xmatrix,vishwaprakashmishra/xmatrix,TouK/vumi,harrissoerja/vumi,TouK/vumi,harrissoerja/vumi