Mermaid is a trendy diagramming tool. A year ago, it was integrated into the Markdown rendering of GitHub. It is also integrated into several editors (see “Include diagrams in your Markdown files with Mermaid” for more information).
What can you do, however, if you use a different editor? What if you want to use your Markdown document in an environment that does not integrate Mermaid yet? What can you do if the diagram is not Mermaid but PlantUML, Graphviz, or any other diagramming tool?