| zoo.small -- same as zoo but with only the important features

|    3. feathers		Boolean
|    5. milk		Boolean
|    6. airborne		Boolean
|    8. predator		Boolean
|   10. backbone		Boolean
|   13. fins		Boolean
|   14. legs		Numeric (set of values: {0,2,4,5,6,8})
|   15. tail		Boolean

1, 2, 3, 4, 5, 6, 7.	| classes ("type")

	feathers:	0, 1.
	milk:		0, 1.
	airborne:	0, 1.
	predator:	0, 1.
	backbone:	0, 1.
	fins:		0, 1.
	legs:		0, 2, 4, 5, 6, 8.
	tail:		0, 1.