def build_dict_parameter_parts(configuration, *parameters, **defaults):
    """
    Construct command parts for one or more parameters, each of which constitutes an assignment of
    the form `key=value`.

    Parameters
    ----------
    configuration : dict
        configuration
    parameters : list
        list of parameters to create command line arguments for
    defaults : dict
        default values to use if a parameter is missing

    Yields
    ------
    argument : str
        command line argument
    """
    for parameter in parameters:
        for key, value in configuration.pop(parameter, {}).items():
            yield '--%s=%s=%s' % (parameter, key, value)