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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def discover(cls, path, depth="0"):
 """Discover a list of collections under the given ``path``. If ``depth`` is "0", only the actual object under ``path`` is returned. If ``depth`` is anything but "0", it is considered as "1" and direct children are included in the result. The ``path`` is relative. The root collection "/" must always exist. """


        # Path should already be sanitized
        attributes = _get_attributes_from_path(path)

        try:
            if len(attributes) == 3:
                # If an item, create a collection for the item.
                item = attributes.pop()
                path = "/".join(attributes)
                collection = cls(path, _is_principal(path))
                yield collection.get(item)
                return

            collection = cls(path, _is_principal(path))
        except api.exceptions.DoesNotExist:
            return

        yield collection

        if depth == "0":
            return

        if len(attributes) == 0:
            yield cls(posixpath.join(path, cls.user), principal=True)
        elif len(attributes) == 1:
            for journal in cls.etesync.list():
                if journal.collection.TYPE in (api.AddressBook.TYPE, api.Calendar.TYPE, api.TaskList.TYPE):
                    yield cls(posixpath.join(path, journal.uid), principal=False)
        elif len(attributes) == 2:
            for item in collection.list():
                yield collection.get(item)

        elif len(attributes) > 2:
            raise RuntimeError("Found more than one attribute. Shouldn't happen")