Different conductivity of two volumes


I have a 3D domain of one box and a subdomain (volume) of a strange shape in the inside. I want to apply different conductivity values in the two volumes. Is there any way to do this by using flags of the two volumes?
For example :

import matplotlib.pyplot as plt
from dolfin import *
import numpy as np
import random

mesh = Mesh(“dolfinmesh.xml”)
mesh_file_volume = MeshFunction(‘size_t’, mesh ,“dolfinmesh_volume_meshvalue.xml”)

for cell in range(mesh.num_cells()):
#inside_volume == 10 and c0 is conductivity coefficient

if mesh_file_volume[cell] == 10:
	c0[cell] = 0.02

	c0[cell] = 1.0

Thank you in advance!

See: How to define different materials / importet 3D geometry (gmsh)