diff --git a/lib/cretonne/meta/cdsl/__init__.py b/lib/cretonne/meta/cdsl/__init__.py
index 247b970675..44445268ea 100644
--- a/lib/cretonne/meta/cdsl/__init__.py
+++ b/lib/cretonne/meta/cdsl/__init__.py
@@ -13,5 +13,47 @@ camel_re = re.compile('(^|_)([a-z])')
 
 def camel_case(s):
     # type: (str) -> str
-    """Convert the string s to CamelCase"""
+    """Convert the string s to CamelCase:
+        >>> camel_case('x')
+        'X'
+        >>> camel_case('camel_case')
+        'CamelCase'
+    """
     return camel_re.sub(lambda m: m.group(2).upper(), s)
+
+
+def is_power_of_two(x):
+    # type: (int) -> bool
+    """Check if `x` is a power of two:
+        >>> is_power_of_two(0)
+        False
+        >>> is_power_of_two(1)
+        True
+        >>> is_power_of_two(2)
+        True
+        >>> is_power_of_two(3)
+        False
+    """
+    return x > 0 and x & (x-1) == 0
+
+
+def next_power_of_two(x):
+    # type: (int) -> int
+    """
+    Compute the next power of two that is greater than `x`:
+        >>> next_power_of_two(0)
+        1
+        >>> next_power_of_two(1)
+        2
+        >>> next_power_of_two(2)
+        4
+        >>> next_power_of_two(3)
+        4
+        >>> next_power_of_two(4)
+        8
+    """
+    s = 1
+    while x & (x + 1) != 0:
+        x |= x >> s
+        s *= 2
+    return x + 1
diff --git a/lib/cretonne/meta/cdsl/test_package.py b/lib/cretonne/meta/cdsl/test_package.py
new file mode 100644
index 0000000000..b66d60d694
--- /dev/null
+++ b/lib/cretonne/meta/cdsl/test_package.py
@@ -0,0 +1,8 @@
+from __future__ import absolute_import
+import doctest
+import cdsl
+
+
+def load_tests(loader, tests, ignore):
+    tests.addTests(doctest.DocTestSuite(cdsl))
+    return tests
diff --git a/lib/cretonne/meta/cdsl/typevar.py b/lib/cretonne/meta/cdsl/typevar.py
index d14866cf77..580d367f51 100644
--- a/lib/cretonne/meta/cdsl/typevar.py
+++ b/lib/cretonne/meta/cdsl/typevar.py
@@ -6,7 +6,7 @@ polymorphic by using type variables.
 """
 from __future__ import absolute_import
 import math
-from . import types
+from . import types, is_power_of_two
 
 try:
     from typing import Tuple, Union # noqa
@@ -20,11 +20,6 @@ MAX_LANES = 256
 MAX_BITS = 64
 
 
-def is_power_of_two(x):
-    # type: (int) -> bool
-    return x > 0 and x & (x-1) == 0
-
-
 def int_log2(x):
     # type: (int) -> int
     return int(math.log(x, 2))
diff --git a/lib/cretonne/meta/constant_hash.py b/lib/cretonne/meta/constant_hash.py
index 38911278ed..8c3c355aa1 100644
--- a/lib/cretonne/meta/constant_hash.py
+++ b/lib/cretonne/meta/constant_hash.py
@@ -6,6 +6,7 @@ don't attempt parfect hashing, but simply generate an open addressed
 quadratically probed hash table.
 """
 from __future__ import absolute_import
+from cdsl import next_power_of_two
 
 
 def simple_hash(s):
@@ -24,27 +25,6 @@ def simple_hash(s):
     return h
 
 
-def next_power_of_two(x):
-    """
-    Compute the next power of two that is greater than `x`:
-        >>> next_power_of_two(0)
-        1
-        >>> next_power_of_two(1)
-        2
-        >>> next_power_of_two(2)
-        4
-        >>> next_power_of_two(3)
-        4
-        >>> next_power_of_two(4)
-        8
-    """
-    s = 1
-    while x & (x + 1) != 0:
-        x |= x >> s
-        s *= 2
-    return x + 1
-
-
 def compute_quadratic(items, hash_function):
     """
     Compute an open addressed, quadratically probed hash table containing