Fix __mul__

lib.py

@@ -13,12 +13,12 @@ class Pixel(namedtuple('Pixel', ['r', 'g', 'b'])):
 			self.b + other.b,
 			)
 	def __mul__(self, other):
-		if not isinstance(other, int) or not isinstance(other, float):
+		if not isinstance(other, int) and not isinstance(other, float):
 			raise ValueError('Can only multiply by number')
 		return Pixel(
-			other*pixel.r,
-			other*pixel.g,
-			other*pixel.b,
+			other*self.r,
+			other*self.g,
+			other*self.b,
 			)
 
 def weighted_average(p1, w1, p2, w2):