Added Usecases to assign, edit and unassign Lag Times to the ifcopenshell.api

src/ifcopenshell-python/ifcopenshell/api/sequence/edit_sequence.py

@@ -0,0 +1,10 @@
+class Usecase:
+    def __init__(self, file, **settings):
+        self.file = file
+        self.settings = {"rel_sequence": None, "attributes": {}}
+        for key, value in settings.items():
+            self.settings[key] = value
+
+    def execute(self):
+        for name, value in self.settings["attributes"].items():
+            setattr(self.settings["rel_sequence"], name, value)