code: def readin_rho(filename, rhofile=True, aniso=False):
      
      if aniso:
          a = [[0, 1, 2], [2, 3, 4]]
      else:
          a = [0, 2]
      if rhofile:
          if filename is None:
              filename = 'rho/rho.dat'
          with open(filename, 'r') as fid:
              mag = np.loadtxt(fid, skiprows=1, usecols=(a[0]))
  
      else:
          if filename is None:
              filename = read_iter()
          with open(filename, 'r') as fid:
              mag = np.power(10, np.loadtxt(fid, skiprows=1, usecols=(a[1])))
  
      return mag
docs: Read in the values of the resistivity in Ohmm.
      The format is variable: rho-file or mag-file.