---
props.types = {
    'required_string': str,
    'optional_number': Optional[int],
    'default_number': int,
}
props.defaults = {
    'default_number': 10,
}

props['new_number'] = props['default_number'] * 2
---

The context contains:

Required string: {{ required_string }}
Optional number: {{ optional_number }}
Default number: {{ default_number }}
New number: {{ new_number }}