code: def _get_shared_memory_size_in_M():
      try:
          df_infos = os.popen(SHM_QUERY_CMD).readlines()
      except:
          return None
      else:
          shm_infos = []
          for df_info in df_infos:
              info = df_info.strip()
              if info.find(SHM_KEY) >= 0:
                  shm_infos.append(info.split())
  
          if len(shm_infos) == 0:
              return None
          elif len(shm_infos) == 1:
              return _parse_size_in_M(shm_infos[0][3])
          else:
              default_mount_infos = [
                  si for si in shm_infos if si[-1] == SHM_DEFAULT_MOUNT
              ]
              if default_mount_infos:
                  return _parse_size_in_M(default_mount_infos[0][3])
              else:
                  return max(
                      [_parse_size_in_M(si[3]) for si in shm_infos]
                  )
  
label_desc: Use image node_id 2 for calling a global function with example usage: _get_shared_memory_size_in_M() and returns: None, None, _parse_size_in_M, _parse_size_in_M, max