diff --git a/pyerrors/correlators.py b/pyerrors/correlators.py
index cb40be1a..abc4b0a9 100644
--- a/pyerrors/correlators.py
+++ b/pyerrors/correlators.py
@@ -69,10 +69,10 @@ class Corr:
 
         if isinstance(data_input, list):
 
-            if all([(isinstance(item, Obs) or isinstance(item, CObs)) for item in data_input]):
+            if all([isinstance(item, (Obs, CObs)) for item in data_input]):
                 _assert_equal_properties(data_input)
                 self.content = [np.asarray([item]) for item in data_input]
-            if all([(isinstance(item, Obs) or isinstance(item, CObs)) or item is None for item in data_input]):
+            if all([isinstance(item, (Obs, CObs)) or item is None for item in data_input]):
                 _assert_equal_properties([o for o in data_input if o is not None])
                 self.content = [np.asarray([item]) if item is not None else None for item in data_input]
                 self.N = 1
@@ -735,7 +735,7 @@ class Corr:
             else:
                 ax1.set_ylim(y_range)
         if comp:
-            if isinstance(comp, Corr) or isinstance(comp, list):
+            if isinstance(comp, (Corr, list)):
                 for corr in comp if isinstance(comp, list) else [comp]:
                     x, y, y_err = corr.plottable()
                     plt.errorbar(x, y, y_err, label=corr.tag, mfc=plt.rcParams['axes.facecolor'])
@@ -846,7 +846,7 @@ class Corr:
                     newcontent.append(self.content[t] + y.content[t])
             return Corr(newcontent)
 
-        elif isinstance(y, Obs) or isinstance(y, int) or isinstance(y, float) or isinstance(y, CObs):
+        elif isinstance(y, (Obs, int, float, CObs)):
             newcontent = []
             for t in range(self.T):
                 if (self.content[t] is None):
@@ -869,7 +869,7 @@ class Corr:
                     newcontent.append(self.content[t] * y.content[t])
             return Corr(newcontent)
 
-        elif isinstance(y, Obs) or isinstance(y, int) or isinstance(y, float) or isinstance(y, CObs):
+        elif isinstance(y, (Obs, int, float, CObs)):
             newcontent = []
             for t in range(self.T):
                 if (self.content[t] is None):
@@ -900,7 +900,7 @@ class Corr:
                 raise Exception("Division returns completely undefined correlator")
             return Corr(newcontent)
 
-        elif isinstance(y, Obs) or isinstance(y, CObs):
+        elif isinstance(y, (Obs, CObs)):
             if isinstance(y, Obs):
                 if y.value == 0:
                     raise Exception('Division by zero will return undefined correlator')
@@ -916,7 +916,7 @@ class Corr:
                     newcontent.append(self.content[t] / y)
             return Corr(newcontent, prange=self.prange)
 
-        elif isinstance(y, int) or isinstance(y, float):
+        elif isinstance(y, (int, float)):
             if y == 0:
                 raise Exception('Division by zero will return undefined correlator')
             newcontent = []
@@ -937,7 +937,7 @@ class Corr:
         return self + (-y)
 
     def __pow__(self, y):
-        if isinstance(y, Obs) or isinstance(y, int) or isinstance(y, float) or isinstance(y, CObs):
+        if isinstance(y, (Obs, int, float, CObs)):
             newcontent = [None if (item is None) else item**y for item in self.content]
             return Corr(newcontent, prange=self.prange)
         else:
diff --git a/pyerrors/input/hadrons.py b/pyerrors/input/hadrons.py
index 371d1525..cea7fb81 100644
--- a/pyerrors/input/hadrons.py
+++ b/pyerrors/input/hadrons.py
@@ -1,7 +1,7 @@
 import os
+from collections import Counter
 import h5py
 import numpy as np
-from collections import Counter
 from ..obs import Obs, CObs
 from ..correlators import Corr
 
diff --git a/pyerrors/input/json.py b/pyerrors/input/json.py
index cdf203f2..c6d0e3cc 100644
--- a/pyerrors/input/json.py
+++ b/pyerrors/input/json.py
@@ -1,12 +1,12 @@
 import json
 import gzip
-import numpy as np
 import getpass
 import socket
 import datetime
 import platform
 import warnings
 import re
+import numpy as np
 from ..obs import Obs
 from ..covobs import Covobs
 from ..correlators import Corr
diff --git a/pyerrors/input/openQCD.py b/pyerrors/input/openQCD.py
index 1c875c1c..b3b8da04 100644
--- a/pyerrors/input/openQCD.py
+++ b/pyerrors/input/openQCD.py
@@ -2,8 +2,8 @@ import os
 import fnmatch
 import re
 import struct
-import numpy as np  # Thinly-wrapped numpy
 import warnings
+import numpy as np  # Thinly-wrapped numpy
 import matplotlib.pyplot as plt
 from matplotlib import gridspec
 from ..obs import Obs