I represent a finite arithmetic progression.

	adding
	add:

	comparing
	= hash hashMappedBy:

	copying
	copy shallowCopy

	enumerating
	collect: do: reverseDo:

	printing
	printOn: storeOn:

	private
	setFrom:to:by: species valuesInclude:

	removing
	remove:

	accessing	top
	at: Answer the anInteger'th element.
	at:put: Storing into an Interval is not allowed.
	first Refer to the comment in SequenceableCollection|first.
	includes: Determine if aNumber is an element of this interval.
	increment Answer the receiver's interval increment.
	last Refer to the comment in SequenceableCollection|last.
	rangeIncludes: Return true if the number lies in the interval between start and stop.
	size Answer how many elements the receiver contains.

	adding	top
	add: Adding to an Interval is not allowed.

	comparing	top
	= Answer true if my species and anInterval species are equal, and if our starts, steps and sizes are equal.
	hash Hash is reimplemented because = is implemented.
	hashMappedBy: My hash is independent of my oop.

	copying	top
	copy Return a copy of me. Override the superclass because my species is Array and copy, as inherited from SequenceableCollection, uses copyFrom:to:, which creates a new object of my species.
	shallowCopy Without this method, #copy would return an array instead of a new interval. The whole problem is burried in the class hierarchy and every fix will worsen the problem, so once the whole issue is resolved one should come back to this method fix it.

	enumerating	top
	collect: Evaluate aBlock with each of the receiver's elements as the argument. Collect the resulting values into a collection like the receiver. Answer the new collection.
	do: Refer to the comment in Collection|do:.
	reverseDo: Evaluate aBlock for each element of my interval, in reverse order.

	printing	top
	printOn: Append a sequence of characters that identify the receiver to aStream.
	storeOn: This is possible because we know numbers store and print the same.

	private	top
	setFrom:to:by:
	species Answer the preferred class for reconstructing the receiver. For example, collections create new collections whenever enumeration messages such as collect: or select: are invoked. The new kind of collection is determined by the species of the original collection. Species and class are not always the same. For example, the species of Interval is Array.
	valuesInclude: Private - answer whether or not aNumber is one of the enumerated values in this interval.

	removing	top
	remove: Removing from an Interval is not allowed.

	instance creation	top
	from:to: Answer an instance of me, starting at startNumber, ending at stopNumber, and with an interval increment of 1.
	from:to:by: Answer an instance of me, starting at startNumber, ending at stopNumber, and with an interval increment of stepNumber.
	new Primitive. Create and answer with a new instance of the receiver (a class) with no indexable fields. Fail if the class is indexable. Override SequenceableCollection new. Essential. See Object documentation whatIsAPrimitive.
	newFrom: Answer an instance of me containing the same elements as aCollection.