feat: Ch02 Fourier Series

Change-Id: I504c9334eeee25dbafadba9bccae6c3cfcd22acc
diff --git a/dcs/frames/__init__.py b/dcs/frames/__init__.py
index 533546c..f6aa703 100644
--- a/dcs/frames/__init__.py
+++ b/dcs/frames/__init__.py
@@ -8,11 +8,13 @@
 from . import base
 
 from .ch02_phasor import Ch02PhasorWindow
+from .ch02_fourier import Ch02FourierWindow
 
 
 def get_windows() -> List[Type[base.Window]]:
     return [
         Ch02PhasorWindow,
+        Ch02FourierWindow,
     ]