code: def get_clusters(pdb_id):
      
      out = get_info(pdb_id, url_root = 'http://www.rcsb.org/pdb/rest/representatives?structureId=')
      out = to_dict(out)
      return remove_at_sign(out['representatives'])
docs: Return cluster related web services of given PDB_ID
  
      Parameters
      ----------
  
      pdb_id : string
          A 4 character string giving a pdb entry of interest
  
      Returns
      -------
  
      out : dict
          A dictionary containing the representative clusters for the specified PDB ID
  
      Examples
      --------
  
      >>> clusts = get_clusters('4hhb.A')
      >>> print(clusts)
      {'pdbChain': {'@name': '2W72.A'}}