namedtuple subclasses should set __slots__=()

src/c3nav/mapdata/render/engines/opengl.py

@@ -21,6 +21,8 @@ class RenderContext(namedtuple('RenderContext', ('width', 'height', 'ctx', 'prog
     """
     A OpenGL Render Context with program and framebuffer. Can only be used by thread that created it.
     """
+    __slots__ = ()
+
     @classmethod
     def create(cls, width, height):
         ctx = ModernGL.create_standalone_context()

src/c3nav/mapdata/render/geometry/mesh.py

@@ -4,6 +4,7 @@ import numpy as np
 
 
 class Mesh(namedtuple('Mesh', ('top', 'sides', 'bottom'))):
+    __slots__ = ()
     empty_faces = np.empty((0, 3, 3)).astype(np.int32)
 
     def tolist(self):