from typing import Dict


def add_prefix_to_param(prefix:str, param_grid:dict) -> Dict[str,list]:
    """
    Create a param_grid for Pipeline from an "ordinary" param_grid.

    :param prefix: name of the step
    :param param_grid: ordinary grid_param
    :return: modified dict
    """
    return { "%s__%s" % (prefix,k): v for k,v in param_grid.items()}