def str_rea_metabolites(rea_metbolites):
    """
    convert reaction.metabolites to str

    :param rea_metbolites: reaction.metabolites a special dictionary
    :return: a str of rea_metbolites
    eval(str_rea_metabolites(rea_metbolites)) could be a normal dictionary
    """
    temp_dic = {}
    for k, v in rea_metbolites.items():
        temp_dic[k.id] = v
    str_mets = str(temp_dic)
    return str_mets
