title: What are the mechanisms and idioms of code re-use in OpenSCAD?
body: <p>I designed few simple 3D parts with OpenSCAD and I would like to move on to more complex parts now. As in most other programming languages, that would naturally include starting to re-use code that others have written before. Such as functions for round/bevel edges, infill corners, beziers curves and some common parts like screws, bolts.</p>
  <p>How does that work in OpenSCAD? Specifically: What are the language features, idioms and officially recommended good practices of how code reuse is achieved in OpenSCAD?</p>
  <p>(You are welcome to include pointers to good examples. But the question is about the mechanisms and good practices for code reuse in OpenSCAD, not about specific code that can be reused.)</p>