Function default_auto_escape_callback 

pub fn default_auto_escape_callback(name: &str) -> AutoEscape

The default logic for auto escaping based on file extension.

• Html: .html, .htm, .xml
• Json: .json, .json5, .js, .yaml, .yml
• None: all others

Additionally .j2, .jinja and .jinja2 as final extension is ignored. So .html.j2 is the considered the same as .html.