d([5.1, 3.5, 1.4, 0.2, 'Iris-setosa'], [5.1, 3.5, 1.4, 0.2, 'Iris-setosa']) = 0.000
d([5.1, 3.5, 1.4, 0.2, 'Iris-setosa'], [?, 3.5, 1.4, 0.2, 'Iris-setosa'])   = 0.778
d([?, 3.5, 1.4, 0.2, 'Iris-setosa'],   [?, 3.5, 1.4, 0.2, 'Iris-setosa'])   = 1.167

d([7.0, 3.2, 4.7, 1.4, 'Iris-versicolor'], [7.0, 3.2, 4.7, 1.4, 'Iris-versicolor']) = 0.000
d([7.0, 3.2, 4.7, 1.4, 'Iris-versicolor'], [?, 3.2, 4.7, 1.4, 'Iris-versicolor'])   = 1.179
d([?, 3.2, 4.7, 1.4, 'Iris-versicolor'],   [?, 3.2, 4.7, 1.4, 'Iris-versicolor'])   = 1.167

d(['young', 'myope', 'no', 'reduced', 'none'], ['young', 'myope', 'no', 'reduced', 'none']) = 0.000
d(['young', 'myope', 'no', 'reduced', 'none'], ['?', 'myope', 'no', 'reduced', 'none'])   = 0.816
d(['?', 'myope', 'no', 'reduced', 'none'],   ['?', 'myope', 'no', 'reduced', 'none'])   = 0.816

