public boolean contains(int id) { return containsKey(id);
public boolean contains(DocumentSet other) { if (other.size() > size()) return false; DocumentImpl d; boolean equal = false; for (Iterator i = other.iterator(); i.hasNext();) { d = (DocumentImpl) i.next(); if (containsKey(d.docId)) equal = true; else equal = false; } return equal;
	public boolean contains(int id) {		return containsKey(id);	}