[0.06, 1], {"Ca":8.75, "a":2.000, "b":1.000, "c":1.000}
[0.48, 1], {"Ca":?, "b":2.000, "d":1.000}
[0.39, 1], {"Ca":7.78}
[0.57, 1], {"Ca":8.22, "c":13.000}

[0.06, 1], {"Ca":8.75, "a":2.000, "b":1.000, "c":1.000}
[0.48, 1], {"Ca":?, "b":2.000, "d":1.000}
[0.39, 1], {"Ca":7.78}
[0.57, 1], {"Ca":8.22, "c":13.000}
All metas:  [Orange.feature.Continuous 'Ca', Orange.feature.Continuous 'a', Orange.feature.Continuous 'b', Orange.feature.Continuous 'c', Orange.feature.Continuous 'd']
Required metas:  [Orange.feature.Continuous 'Ca']
Optional metas:  [Orange.feature.Continuous 'a', Orange.feature.Continuous 'b', Orange.feature.Continuous 'c', Orange.feature.Continuous 'd']
