Fix Pylint warnings

lisainstrument/hexagon.py

@@ -68,7 +68,6 @@ class Hexagon():
         # initialize signal-combination attributes
         self.three_signal_combination = None
 
-
     def simulate(self):
         """Run a simulation, and generate all intermediary signals.
 
@@ -109,7 +108,6 @@ class Hexagon():
         self.three_signal_combination = self.carrier_beatnotes[:,0] \
             + self.carrier_beatnotes[:,1] + self.carrier_beatnotes[:,2]
 
-
     def write(self, output='measurements.h5', mode='w'):
         """Write simulation results.
 
@@ -131,7 +129,6 @@ class Hexagon():
             self._write_attr(hdf5, 'carrier_beatnote_fluctuations', indices=self.BEATNOTES)
             self._write_attr(hdf5, 'three_signal_combination')
 
-            
     def _write_attr(self, hdf5, dataset, indices=None):
         """Write a single object attribute on ``hdf5``.