diff --git a/pystencils/data_types.py b/pystencils/data_types.py
index 84af2f7f5512ab71dd6f88e29b178f4842c37c4c..9bf8375bf33d325b22e727b88a49c941b44347af 100644
--- a/pystencils/data_types.py
+++ b/pystencils/data_types.py
@@ -79,9 +79,10 @@ def assumptions_from_dtype(dtype):
 
 # noinspection PyPep8Naming
 class address_of(sp.Function):
-    # TODO: ask Martin
+    # DONE: ask Martin
     # TODO: documentation
     # TODO: move function to `functions.py`
+    # this is '&' in C
     is_Atom = True
 
     def __new__(cls, arg):
@@ -644,7 +645,8 @@ if int(sympy_version[0]) * 100 + int(sympy_version[1]) >= 109:
 
 class Type(sp.Atom):
     # TODO: why is our type system dependent on sympy???
-    # TODO: ask Martin
+    # DONE: ask Martin
+    # TODO: inherits from sp.Atom because of cast function (and maybe others)
     def __new__(cls, *args, **kwargs):
         return sp.Basic.__new__(cls)
 
diff --git a/pystencils/transformations.py b/pystencils/transformations.py
index 1175580f744d827ae0f32702cb0846da6bd7b9f4..0c6d006581eb20df623bc9e0d7c441fe00e4f130 100644
--- a/pystencils/transformations.py
+++ b/pystencils/transformations.py
@@ -805,6 +805,8 @@ def cleanup_blocks(node: ast.Node) -> None:
 
 
 class KernelConstraintsCheck:
+    # TODO: Logs
+    # TODO: specification
     """Checks if the input to create_kernel is valid.
 
     Test the following conditions: