Add API documentation for the material module

src/ifcopenshell-python/ifcopenshell/api/material/edit_assigned_material.py

@@ -18,11 +18,27 @@
 
 
 class Usecase:
-    def __init__(self, file, **settings):
+    def __init__(self, file, element=None, attributes=None):
+        """Edits the attributes of an IfcMaterial
+
+        For more information about the attributes and data types of an
+        IfcMaterial, consult the IFC documentation.
+
+        :param element: The IfcMaterial entity you want to edit
+        :type element: ifcopenshell.entity_instance.entity_instance
+        :param attributes: a dictionary of attribute names and values.
+        :type attributes: dict, optional
+        :return: None
+        :rtype: None
+
+        Example::
+
+            concrete = ifcopenshell.api.run("material.add_material", model, name="CON01", category="concrete")
+            ifcopenshell.api.run("material.edit_assigned_material", model,
+                element=concrete, attributes={"Description": "40MPA concrete with broom finish"})
+        """
         self.file = file
-        self.settings = {"element": None, "attributes": {}}
-        for key, value in settings.items():
-            self.settings[key] = value
+        self.settings = {"element": element, "attributes": attributes or {}}
 
     def execute(self):
         for name, value in self.settings["attributes"].items():