code: def from_file(xmu_dat_file="xmu.dat", feff_inp_file="feff.inp"):
          
          data = np.loadtxt(xmu_dat_file)
          header = Header.from_file(feff_inp_file)
          parameters = Tags.from_file(feff_inp_file)
          pots = Potential.pot_string_from_file(feff_inp_file)
          # site index (Note: in feff it starts from 1)
          if "RECIPROCAL" in parameters:
              absorbing_atom = parameters["TARGET"]
          # species symbol
          else:
              absorbing_atom = pots.splitlines()[3].split()[2]
          return Xmu(header, parameters, absorbing_atom, data)
docs: Get Xmu from file.
  
          Args:
              xmu_dat_file (str): filename and path for xmu.dat
              feff_inp_file (str): filename and path of feff.inp input file
  
          Returns:
               Xmu object