Use multipledispatch to define divide (plus dostring for add)

mapytex/calculus/core/compute/add.py

@@ -10,19 +10,19 @@
 Adding MO
 """
 
+from multipledispatch import Dispatcher
 from ..tree import Tree
 from ..MO.mo import MO, MOnumber
 from ..MO.fraction import MOFraction
 from .exceptions import AddError
 from .arithmetic import lcm
 from .type_filter import args_are
-from multipledispatch import Dispatcher
 
 add_doc = """ Adding MOs
 
-    :param left: left MO
-    :param right: right MO
-    :return: Tree or MO
+:param left: left MO
+:param right: right MO
+:return: Tree or MO
 
 """
 add = Dispatcher("add", doc=add_doc)