code: def is_submodule_included(src, tgt):
      
      if tgt is None or not hasattr(tgt, 'i_orig_module'):
          return True
      if (tgt.i_orig_module.keyword == 'submodule' and
          src.i_orig_module != tgt.i_orig_module and
          src.i_orig_module.i_modulename == tgt.i_orig_module.i_modulename):
          if src.i_orig_module.search_one('include',
                                          tgt.i_orig_module.arg) is None:
              return False
      return True
docs: Check that the tgt's submodule is included by src, if they belong
      to the same module.