one ( expr : OclExpression ) : Boolean

Returns true if there is only one element contained in self that validates the condition expr, false otherwise.

Expression	Result
Sequence{1.2, 2.3, 5.2, 0.9}->one(self < 1)	true
Sequence{1.2, 2.3, 5.2, 0.9}->one(self < 2)	false