An array of strings is appropriate for typical use cases, with the first item in the array being the "opening" delimiter, and the second item being the "closing" delimiter. In cases when multiple delimiters are required, e.g. --- or ~~~, an array of arrays may be passed in, where the first array will be used as opening delimiters and the second array will be used as closing delimiters.
Additionally, when multiple arrays are passed in the generated delimiters will be wrapped in non-capturing RegExp groups. For example, this: