Fix linting

Signed-off-by: Umberto Zerbinati <[email protected]>

ngsPETSc/utils/firedrake.py

@@ -8,11 +8,10 @@
 except ImportError:
     fd = None
 
+from fractions import Fraction
 import warnings
 import numpy as np
 from petsc4py import PETSc
-from fractions import Fraction
-from copy import deepcopy
 
 import netgen
 import netgen.meshing as ngm
@@ -240,7 +239,7 @@ def NetgenHierarchy(ngmesh, levs, order=1, digits=8, adaptive=False, comm=fd.COM
     #Curving linear mesh
     mesh = fd.Mesh(mesh.curve_field(order=order, digits=digits))
     meshes += [mesh]
-    for lv in range(levs):
+    for _ in range(levs):
         #Streightening the mesh
         ngmesh.Curve(1)
         #We refine the netgen mesh uniformly
@@ -273,4 +272,4 @@ def NetgenHierarchy(ngmesh, levs, order=1, digits=8, adaptive=False, comm=fd.COM
     fine_to_coarse_cells = dict((Fraction(i, refinements_per_level), f2c)
                             for i, f2c in enumerate(fine_to_coarse_cells))
     return fd.HierarchyBase(meshes, coarse_to_fine_cells, fine_to_coarse_cells,
-                         refinements_per_level, nested=False)
+                         refinements_per_level, nested=False)