reduce
inline fun <ID : Any, T> Field<ID, T>.reduce(crossinline reducer: Reducer<FieldEntry<ID, T>>): FieldEntry<ID, T>?
Reduces the field entries to a single value using the given reducer function, excluding the local element.
This function performs a reduction over the field entries (excluding the local one), combining them pairwise using reducer. If the field contains no neighbor entries, the result is null.
Return
the result of the reduction, or null if the field has no neighbors.
Parameters
reducer
a binary operation that reduces two entries into one.