Generate useful extension when filtering enum values

IsCase.stencil

{% for enum in types.enums %}
// MARK: {{ enum.name }}
extension {{ enum.name }} {
  {% for case in enum.cases %}
  {{ enum.accessLevel }} var is{{ case.name|upperFirstLetter }}: Bool {
      switch self { case .{{ case.name }}: return true; default: return false; }
  }
  {% endfor %}
}
{% endfor %}