NewSliceStream returns a new stream.

ToStream helper converts a slice into a Stream.

EXERCISE 5.3 END OMIT Pair of two values.

SliceStream is a stream implementation for slices.

EXERCISE 5.3 START OMIT Any is a shortcut for the empty interface{}.

Stream interface is implemented for container types.

Accumulator function returns a combined element.

Mapper function maps a value to another value.

Predicate function returns true if a given element should be filtered.