@foreach
Description:
Calls func for each [alias@Extension].
Parameters:
| this | A ExtensionSet. | 
| func | A function call for each extension. | 
| data | Optional data to be passed to the function or null. | 
Calls func for each [alias@Extension].
| this | A ExtensionSet. | 
| func | A function call for each extension. | 
| data | Optional data to be passed to the function or null. |