If an S and an I and an O and a U - With an X at the end...

If an S and an I and an O and a U - With an X at the end spell Su; And an E and a Y and an E spell I, - Pray what is a speller to do? Then, if also an S and an I and a G - And an HED spell side, There's nothing much left for a speller to do, But to g