Fix formatting

logistic_map.py

@@ -1,13 +1,14 @@
-import numpy as np
+from itertools import islice
+
 import matplotlib.pyplot as plt
-from itertools import islice 
+import numpy as np
 
 
 class LogisticMap(object):
     def __init__(self, r, x0):
         self.r = r
         self.x0 = x0
-    
+
     def compute(self, x):
         return self.r * x * (1 - x)