ref: ba4a1c07f1bc7622f8a3dcd4f2d383f4ec70fc1c dir: /test/t.aeiouy/
/^[^aeiouy]*a[^aeiouy]*e[^aeiouy]*i[^aeiouy]*o[^aeiouy]*u[^aeiouy]*y[^aeiouy]*$/