@classmethod
def get_jointer(cls, df_type):
    """
        @param::left: the type of left dataframe in string
        @param::right: the type of right dataframe in string
        @param::out: the output dataframe type in string
        return boolean value indicates whether or not the two dataframes can be joined.
        """
    for j in cls.__jointers__:
        if j.is_capable(df_type):
            return j
