I saw three witches

Well, I got the data hacked into shape for this month -- now I need a method before next month that doesn't involve me comparing two lists of 1.5K patients by hand again.

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I Saw Three Witches

I saw three witches
That bowed down like barley,
And took to their brooms 'neath a louring sky,
And, mounting a storm-cloud,
Aloft on its margin,
Stood black in the silver as up they did fly.

I saw three witches
That mocked the poor sparrows
They carried in cages of wicker along,
Till a hawk from his eyrie
Swooped down like an arrow,
And smote on the cages, and ended their song.

I saw three witches
That sailed in a shallop
All turning their heads with a truculent smile
Till a bank of green osiers
Concealed their grim faces,
Though I heard them lamenting for many a mile.

I saw three witches
Asleep in a valley,
Their heads in a row, like stones in a flood,
Till the moon, creeping upward,
Looked white through the valley,
And turned them to bushes in bright scarlet bud.

-- Walter de la Mare