Use trump data to build conversion table
        
        symbols : 
            list of symbols:
                will attempt to use units to build the conversion table,
                strings represent symbol names.

def use_trump_data(self, symbols):
        """
        Use trump data to build conversion table
        
        symbols : 
            list of symbols:
                will attempt to use units to build the conversion table,
                strings represent symbol names.
        """
        dfs = {sym.units : sym.df[sym.name] for sym in symbols}
               
        self.build_conversion_table(dfs)