A set of characters. Lookups for inclusion are very fast.

	comparison
	= hash species

	conversion
	complement

	private
	byteArrayMap initialize

	collection ops	top
	add: Include newObject as one of the receiver's elements. Answer newObject. ArrayedCollections cannot respond to this message.
	do: evaluate aBlock with each character in the set
	includes: Answer whether anObject is one of the receiver's elements.
	remove: Remove oldObject from the receiver's elements. Answer oldObject unless no element is equal to oldObject, in which case, raise an error. ArrayedCollections cannot respond to this message.

	comparison	top
	= Answer whether the receiver and the argument represent the same object. If = is redefined in any subclass, consider also redefining the message hash.
	hash Answer an integer hash value for the receiver such that, -- the hash value of an unchanged object is constant over time, and -- two equal objects have equal hash values
	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.

	conversion	top
	complement return a character set containing precisely the characters the receiver does not

	private	top
	byteArrayMap return a ByteArray mapping each ascii value to a 1 if that ascii value is in the set, and a 0 if it isn't. Intended for use by primitives only
	initialize

	instance creation	top
	allCharacters return a set containing all characters
	empty return an empty set of characters
	new Answer a new instance of the receiver (which is a class) with no indexable variables. Fail if the class is indexable.
	newFrom: Create an object that has similar contents to aSimilarObject. If the classes have any instance varaibles with the same names, copy them across. If this is bad for a class, override this method.
	nonSeparators return a set containing everything but the whitespace characters
	separators return a set containing just the whitespace characters