description

# single property

E get single
override

Checks that this iterable has only one element, and returns that element.

Throws a StateError if `this` is empty or has more than one element. This operation will not iterate past the second element.

## Implementation

    E get single {
      if (length == 0) throw IterableElementError.noElement();
      if (length > 1) throw IterableElementError.tooMany();
      return this[0];
    }