Fix PEP8 Indent Error.

Author: duncanhobbs

quantecon/lqcontrol.py

@@ -147,7 +147,7 @@ def __init__(self, Q, R, A, B, C=None, N=None, beta=1, T=None, Rf=None):
 
             if (self.C != 0).any() and beta >= 1:
                 raise ValueError('beta must be strictly smaller than 1 if ' +
-                'T = None and C != 0.')
+                    'T = None and C != 0.')
 
         self.F = None