description

# expand<T> method Null safety

Iterable<T> expand <T>(

1. Iterable<T> f(
   1. E element
   )

)

Expands each element of this Iterable into zero or more elements.

The resulting Iterable runs through the elements returned by `f` for each element of this, in iteration order.

The returned Iterable is lazy, and calls `f` for each element of this every time it's iterated.

Example:

    var pairs = [[1, 2], [3, 4]];
    var flattened = pairs.expand((pair) => pair).toList();
    print(flattened); // => [1, 2, 3, 4];

    var input = [1, 2, 3];
    var duplicated = input.expand((i) => [i, i]).toList();
    print(duplicated); // => [1, 1, 2, 2, 3, 3]

## Implementation

    Iterable<T> expand<T>(Iterable<T> f(E element)) =>
        ExpandIterable<E, T>(this, f);