docs for numba and cuda

src/kyupy/__init__.py

@@ -1,8 +1,8 @@
 """A package for processing and analysis of non-hierarchical gate-level VLSI designs.
 
 The kyupy package itself contains a logger and other simple utility functions.
-In addition, it defines a ``numba`` and a ``cuda`` module that point to the actual modules
-if they are available and point to mocks if numba is not installed.
+In addition, it defines a ``numba`` and a ``cuda`` objects that point to the actual packages
+if they are available and otherwise point to mocks.
 """
 
 import time
@@ -202,5 +202,12 @@ if importlib.util.find_spec('numba') is not None:
         cuda = MockCuda()
 else:
     numba = MockNumba()
+    """If Numba is available on the system, it is the actual ``numba`` package.
+    Otherwise, it simply defines an ``njit`` decorator that does nothing.
+    """
     cuda = MockCuda()
+    """If Numba is installed and Cuda GPUs are available, it is the actual ``numba.cuda`` package.
+    Otherwise, it is an object that defines basic methods and decorators so that cuda-code can still
+    run in the Python interpreter.
+    """
     log.warn('Numba unavailable. Falling back to pure Python.')