update pep8 ifs_sim

csst_ifs_sim/csst_ifs_sim.py

@@ -1887,8 +1887,7 @@ class IFSsimulator():
         :rtype: ndarray
         """
         self.log.info('Generating a flat field...')
-        self.log.info('The flat field has mean value of 1 and a given fluctuations,
-                      usually either 1 or 2 percent defined by sigma= %d...' % sigma)
+        self.log.info('The flat field has mean value of 1 and a given fluctuations, usually either 1 or 2 percent defined by sigma= %d...' % sigma)
 
         np.random.seed(5*self.simnumber)
         self.flat_b = np.random.normal(loc=ave, scale=sigma, size=(2048, 4096))