Add docstrings

xdsl/dialects/arith.py

@@ -197,10 +197,21 @@ def py_operation(lhs: int, rhs: int) -> int | None:
 
     @staticmethod
     def is_right_zero(attr: AnyIntegerAttr) -> bool:
+        """
+        Returns True only when 'attr' is a right zero for the operation
+        https://en.wikipedia.org/wiki/Absorbing_element
+
+        Note that this depends on the operation and does *not* imply that
+        attr.value.data == 0
+        """
         return False
 
     @staticmethod
     def is_right_unit(attr: AnyIntegerAttr) -> bool:
+        """
+        Return True only when 'attr' is a right unit/identity for the operation
+        https://en.wikipedia.org/wiki/Identity_element
+        """
         return False
 
     def __init__(