Chains multiple data sources into a single stream, preserving source order.
Items are emitted in source order: all items from the first source,
then all items from the second source, and so on.
Each source is fully consumed before moving to the next.
Chains multiple data sources into a single stream, preserving source order.
Items are emitted in source order: all items from the first source, then all items from the second source, and so on. Each source is fully consumed before moving to the next.