(I presume'ordinal' meant 'ordinary'.)  I don't know where signature finds the info on built-in type objects   Methods like .append have .__text_signature__.  List does not, and list.__call__.__text_signature is the generic '($self, /, *args, **kwargs)'.  That signature finds it somewhere is a reason for the switch. There is no longer a signature in the first lines of the docstring. So currently, 'list(' only displays "Built-in mutable sequence."

Louie, I verified that for python-coded classes, signature itself gets the info from the __init__ method, so we don't need 'fob = ob.__init__' for python classes either.