description

# fold<T> method Null safety

T fold <T>(

1. T initialValue,
2. T combine(
   1. T previousValue,
   2. E element
   )

)
override

Reduces a collection to a single value by iteratively combining each element of the collection with an existing value

Uses `initialValue` as the initial value, then iterates through the elements and updates the value with each element using the `combine` function, as if by:

    var value = initialValue;
    for (E element in this) {
      value = combine(value, element);
    }
    return value;

Example of calculating the sum of an iterable:

    iterable.fold(0, (prev, element) => prev + element);

## Implementation

    T fold<T>(T initialValue, T combine(T previousValue, E element)) {
      var value = initialValue;
      for (E element in this) value = combine(value, element);
      return value;
    }