Add API documentation for document module

src/ifcopenshell-python/ifcopenshell/api/document/unassign_document.py

@@ -20,14 +20,38 @@ import ifcopenshell
 
 
 class Usecase:
-    def __init__(self, file, **settings):
+    def __init__(self, file, product=None, document=None):
+        """Unassigns a document and a product association
+
+        :param product: The object that the document reference or information is
+            related to.
+        :type product: ifcopenshell.entity_instance.entity_instance
+        :param document: The IfcDocumentReference (typically) or in rare cases
+            the IfcDocumentInformation that is associated with the product
+        :type document: ifcopenshell.entity_instance.entity_instance
+        :return: None
+        :rtype: None
+
+        Example::
+
+            document = ifcopenshell.api.run("document.add_information", model)
+            ifcopenshell.api.run("document.edit_information", model,
+                information=document,
+                attributes={"Identification": "A-GA-6100", "Name": "Overall Plan",
+                "Location": "A-GA-6100 - Overall Plan.pdf"})
+            reference = ifcopenshell.api.run("document.add_reference", model, information=document)
+
+            # Let's imagine storey represents an IfcBuildingStorey for the ground floor
+            ifcopenshell.api.run("document.assign_document", model, product=storey, document=reference)
+
+            # Now let's change our mind and remove the association
+            ifcopenshell.api.run("document.unassign_document", model, product=storey, document=reference)
+        """
         self.file = file
         self.settings = {
-            "product": None,
-            "document": None,
+            "product": product,
+            "document": document,
         }
-        for key, value in settings.items():
-            self.settings[key] = value
 
     def execute(self):
         for rel in self.settings["product"].HasAssociations: