code: def trace_line_numbers(filename, reload_on_change=False):
      
      fullname = cache_file(filename, reload_on_change)
      if not fullname: return None
      e = file_cache[filename]
      if not e.line_numbers:
          if hasattr(coverage.coverage, 'analyze_morf'):
              e.line_numbers = coverage.the_coverage.analyze_morf(fullname)[1]
          else:
              cov = coverage.coverage()
              cov._warn_no_data = False
              e.line_numbers = cov.analysis(fullname)[1]
              pass
          pass
      return e.line_numbers
docs: Return an Array of breakpoints in filename.
      The list will contain an entry for each distinct line event call
      so it is possible (and possibly useful) for a line number appear more
      than once.