@staticmethod
def _normalize(effect: dict) ->dict:
    """
        Normalize effect values (sum equals 1).

        :param effect: (dict) of effect values.
        :return: (dict) of normalized effect values.
        """
    values_sum = sum(effect.values())
    updated_effect = {}
    for k, v in effect.items():
        updated_effect[k] = v / values_sum
    return updated_effect
