Fix comparison with None and equality operator

boxes/__init__.py

@@ -706,7 +706,7 @@ class Boxes:
 
         Flush canvas to disk and convert output to requested format if needed.
         Call after .render()"""
-        if self.ctx == None:
+        if self.ctx is None:
             return
 
         self.ctx.stroke()

boxes/generators/atreus21.py

@@ -87,7 +87,7 @@ class Atreus21(Boxes, Keyboard):
 
     @restore
     def half(self, hole_cb=None, reverse=False):
-        if hole_cb == None:
+        if hole_cb is None:
             hole_cb = self.key
         self.moveTo(self.half_btn, self.half_btn)
         self.apply_callback_on_columns(

boxes/generators/dividertray.py

@@ -449,8 +449,8 @@ class SlotDescription:
     ):
         self.depth = depth
         self.width = width
-        self.start_radius = radius if start_radius == None else start_radius
-        self.end_radius = radius if end_radius == None else end_radius
+        self.start_radius = radius if start_radius is None else start_radius
+        self.end_radius = radius if end_radius is None else end_radius
         self.angle = angle
 
     def __repr__(self):

boxes/generators/keyboard.py

@@ -165,7 +165,7 @@ class Keyboard:
             grid_hole(3, -4, led_hole_size)
 
     def apply_callback_on_columns(self, cb, columns_definition, spacing=None, reverse=False):
-        if spacing == None:
+        if spacing is None:
             spacing = self.STANDARD_KEY_SPACING
         if reverse:
             columns_definition = list(reversed(columns_definition))