Checks to if a symbol exists, by name.
        
        Parameters
        ----------
        symbol : str or Symbol

        Returns
        -------
        bool

def exists(self, symbol):
        """Checks to if a symbol exists, by name.
        
        Parameters
        ----------
        symbol : str or Symbol

        Returns
        -------
        bool
        """

        if isinstance(symbol, str):
            sym = symbol
        elif isinstance(symbol, Symbol):
            sym = symbol.name

        syms = self.ses.query(Symbol).filter(Symbol.name == sym).all()
        if len(syms) == 0:
            return False
        else:
            return True