Write documentation for root API module

src/ifcopenshell-python/ifcopenshell/api/root/remove_product.py

@@ -20,11 +20,33 @@ import ifcopenshell.api
 
 
 class Usecase:
-    def __init__(self, file, **settings):
+    def __init__(self, file, product=None):
+        """Removes a product
+
+        This is effectively a smart delete function that not only removes a
+        product, but also all of its relationships. It is always recommended to
+        use this function to prevent orphaned data in your IFC model.
+
+        For example, geometric representations are removed. Placement
+        coordinates are also removed. Properties are removed. Material, type,
+        containment, aggregation, and nesting relationships are removed (but
+        naturally, the materials, types, containers, etc themselves remain).
+
+        :param product: The IfcProduct to remove.
+        :type product: ifcopenshell.entity_instance.entity_instance
+        :return: None
+        :rtype: None
+
+        Example::
+
+            # We have a wall.
+            wall = ifcopenshell.api.run("root.create_entity", model, ifc_class="IfcWall")
+
+            # No we don't.
+            ifcopenshell.api.run("root.remove_product", model, product=wall)
+        """
         self.file = file
-        self.settings = {"product": None}
-        for key, value in settings.items():
-            self.settings[key] = value
+        self.settings = {"product": product}
 
     def execute(self):
         representations = []