Fix flake8 errors/warnings

qt/python/mantidqt/widgets/sliceviewer/peaksviewer/representation/painter.py

@@ -24,7 +24,8 @@ class EllipticalShell(Patch):
     """
 
     def __str__(self):
-        return f"EllipticalShell(center={self.center}, width={self.width}, height={self.height}, frac_thick={self.frac_thick}, angle={self.angle})"
+        return f"EllipticalShell(center={self.center}, width={self.width}, height={self.height}, " \
+               f"frac_thick={self.frac_thick}, angle={self.angle})"
 
     def __init__(self, center, width, height, frac_thick, angle=0.0, **kwargs):
         """

qt/python/mantidqt/widgets/sliceviewer/peaksviewer/representation/test/test_peaksviewer_representation_ellipsoid.py

@@ -185,7 +185,8 @@ class EllipsoidalIntergratedPeakRepresentationSliceEllipsoidTest(unittest.TestCa
         c = 1
         zp = 0
 
-        slice_transform = lambda x: (x[1], x[0], x[2])
+        def slice_transform(x):
+            return (x[1], x[0], x[2])
 
         expected_slice_origin = (0, 0, 0)
         expected_major_radius = 2