old_contents: from pyxtf.xtf_ctypes import *
  from pyxtf.xtf_io import xtf_read, concatenate_channel
  
  
new_contents: from pyxtf.xtf_ctypes import *
  from pyxtf.xtf_io import xtf_read, xtf_read_gen, concatenate_channel
  
  
subject: Add xtf_read_gen