Fill a task's includes and placeholders: each {{> name}} becomes core template name (one level: an included template's own includes are left as they are), then each {{key}} becomes vars[key].
{{> name}}
name
{{key}}
vars[key]
When a placeholder has no value (naming every missing key), or an included core template does not exist.
Fill a task's includes and placeholders: each
{{> name}}becomes core templatename(one level: an included template's own includes are left as they are), then each{{key}}becomesvars[key].