*** Reference instance:  ['young', 'myope', 'no', 'reduced', 'none']
['young', 'myope', 'no', 'reduced', 'none'], {-3:0.00}
['young', 'myope', 'yes', 'reduced', 'none'], {-3:1.00}
['presbyopic', 'myope', 'no', 'reduced', 'none'], {-3:1.00}
['young', 'hypermetrope', 'no', 'reduced', 'none'], {-3:1.00}
['young', 'myope', 'no', 'normal', 'soft'], {-3:1.00}
