code: def rpc_get_namespace_cost( self, namespace_id, **con_info ):
          
          if not check_namespace(namespace_id):
              return {'error': 'Invalid namespace', 'http_status': 400}
  
          db = get_db_state(self.working_dir)
          res = get_namespace_cost( db, namespace_id )
          db.close()
  
          units = res['units']
          amount = res['amount']
          ns = res['namespace']
  
          if amount is None:
              # invalid 
              return {'error': 'Invalid namespace', 'http_status': 404}
  
          ret = {
              'units': units,
              'amount': amount,
          }
  
          if ns is not None:
              ret['warning'] = 'Namespace already exists'
  
          return self.success_response( ret )
docs: Return the cost of a given namespace, including fees.
          Returns {'amount': ..., 'units': ...}