code: def get_connection(connection='', engine_name=None, connection_type='long', **args):
      
      engine_name = engine_name or __default_engine__
      if '://' in connection:
          d = {
              'connection_string':connection,
              'connection_args':args,
              'connection_type':connection_type,
              }
          
          return engine_manager.add(engine_name, d).engine
      else:
          connection = connection or __default_engine__
          if connection in engine_manager:
              return engine_manager[connection].engine
          else:
              raise Error("Can't find engine %s" % connection)
docs: Creating an NamedEngine or just return existed engine instance
  
      if '://' include in connection parameter, it'll create new engine object
      otherwise return existed engine isntance