single

Returns the one and only element of the sequence.

JavaScript

// 1
Enumerable.create(1)
          .single();

// THROWS EXCEPTION
Enumerable.create()
          .single();

// 22
Enumerable.create(11, 22)
          .single('x => x > 11');

// THROWS EXCEPTION
Enumerable.create(111, 222, 333)
          .single('x => x > 111');