flake8 recommended changes (#164)

pip install --upgrade flake8  # http://flake8.pycqa.org
python2 -m flake8 . --exclude=third_party --ignore=E1,E306 --max-line-length=80

lib/math.py

@@ -68,7 +68,7 @@ def factorial(x):
 
     acc = 1
 
-    for value in range(2,x+1):
+    for value in range(2, x+1):
         acc *= value
 
     return acc
@@ -92,7 +92,7 @@ def frexp(x):
 
 
 def isinf(x):
-    return IsInf(float(x),0)
+    return IsInf(float(x), 0)
 
 
 def isnan(x):
@@ -104,7 +104,7 @@ def ldexp(x, i):
 
 
 def modf(x):
-    #Modf returns (int, frac), but python should return (frac, int).
+    # Modf returns (int, frac), but python should return (frac, int).
     a, b = Modf(float(x))
     return b, a