# FAQs ### Why aren’t the outputs of bricks nested within a Control Flow Brick available outside the Control Flow brick? PixieBrix Control Flow bricks are implemented similar to [closures](https://en.wikipedia.org/wiki/Closure_\(computer_programming\)) in popular programming languages like Javascript. By “freezing” the environment passed into a branch/body of a Control Flow brick and preventing it from modifying the available Output Keys outside of the brick, the behavior of bricks are more predictable (to PixieBrix’s debugger and humans!). Predictability allows use cases like button handlers and rendering sub-panel elements in parallel --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://docs.pixiebrix.com/developing-mods/developer-concepts/control-flow/control-flow-bricks/faqs.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.