An abstract method for finding a :term:`loader` for the specified
module. If this is a top-level import, *path* will be ``None``.
iwse, this is a search for a subpackage or module and *path*
+ Otherwse, this is a search for a subpackage or module and *path*
will be the value of :attr:`__path__` from the parent
package. If a loader cannot be found, ``None`` is returned.