code: func Default(def interface{}) {
  	if a, ok := attributeDefinition(); ok {
  		if a.Type != nil {
  			if !a.Type.CanHaveDefault() {
  				dslengine.ReportError("%s type cannot have a default value", qualifiedTypeName(a.Type))
  			} else if !a.Type.IsCompatible(def) {
  				dslengine.ReportError("default value %#v is incompatible with attribute of type %s",
  					def, qualifiedTypeName(a.Type))
  			} else {
  				a.SetDefault(def)
  			}
  		} else {
  			a.SetDefault(def)
  		}
  	}
  }
docs: // Default can be used in: Attribute
  //
  // Default sets the default value for an attribute.
  // See http://json-schema.org/latest/json-schema-validation.html#anchor10.