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# reduce

Applies an accumulator function over an observable sequence, returning the result of the aggregation as a single element in the result sequence. The specified seed value is used as the initial accumulator value.

For aggregation behavior with incremental intermediate results, see the `scan` method.

## Arguments

1. `accumulator` *(`Function`)*:  An accumulator function to be invoked on each element.
2. `[seed]` *(`Any`)*: The initial accumulator value.

## Returns

*(`Observable`)*: An observable sequence containing a single element with the final accumulator value.

## Example