code: def count_lines_in_file(src_file ):
      
      tot = 0
      res = ''
      try:
          with open(src_file, 'r') as f:
              for line in f:
                  tot += 1
              res = str(tot) + ' recs read'       
      except:
          res = 'ERROR -couldnt open file'
      return res
docs: test function.