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Sequence.exactlyOne(_:)

exactlyOne(_:) ( expression : FilterExpr<Element> ) → Self.Element method [source] ¶ method [source] ¶ exactlyOne(_:)

The one element the filter matches.

Distinguishes "nothing matched" from "several matched", because a caller that meant to address one object needs to know which mistake it made.

Raises

0 declared, 0 inherited