code: function isPreviewContext(context, previewContext) {
    if (previewContext) {
      return context === previewContext;
    }
    return PREVIEW_CONTEXT_KEYWORDS.some(keyword => context.includes(keyword));
  }
docs: Check a given status context string to determine if it provides a link to a
  deploy preview. Checks for an exact match against `previewContext` if given,
  otherwise checks for inclusion of a value from `PREVIEW_CONTEXT_KEYWORDS`.