Pipeline

Pipelines are immutable stage chains; adding a stage creates a new pipeline, minimizing side-effects and enabling easy reuse, as highlighted in the README's 'Immutability' section.

Stages can be any callable, including closures, invokable classes, or classes implementing StageInterface, allowing seamless integration with existing PHP code, as demonstrated in the 'Usage' examples.

Pipelines can be nested as stages within other pipelines, enabling complex, modular workflows, with the README showing how to reuse pipelines in API processing scenarios.

PipelineBuilder facilitates collecting stages before construction, useful for distributed setup, as explained in the 'Pipeline Builders' section.