How to print YAML form in custom block under drupal 8 The accordion section was created in custom block under drupal 8. And I want to show yaml form in description of that accordion section. So, I would like to ask how to print YAML form in custom block.
Install the module insert Block

Enable and configure the insert block text format in 'admin/config/content/formats' 

Make a new block with your form so that your form is available as a block.

In your accordion block you can call your form block with the special insert block tags [block:module=delta]. Make sure the 'insert block' text type is selected.