Runs a Symbol's validity checks.
        
        Parameters
        ----------
        checks : str, [str,], optional
            Only run certain checks.  
        report : bool, optional
            If set to False, the method will return only the result of the
            check checks (True/False).  Set to True, to have a 
            SymbolReport returned as well.
            
        Returns
        -------
        Bool, or a Tuple of the form (Bool, SymbolReport)

def check_validity(self, checks=None, report=True):
        """ Runs a Symbol's validity checks.
        
        Parameters
        ----------
        checks : str, [str,], optional
            Only run certain checks.  
        report : bool, optional
            If set to False, the method will return only the result of the
            check checks (True/False).  Set to True, to have a 
            SymbolReport returned as well.
            
        Returns
        -------
        Bool, or a Tuple of the form (Bool, SymbolReport)
        """        
        if report:
            reportpoints = []
            
        allchecks = []
        
        checks_specified=False
        
        if isinstance(checks, (str, unicode)):
            checks = [checks]
            checks_specified = True
        elif isinstance(checks, (list, tuple)):
            checks_specified = True
        else:
            checks = []
            
        for val in self.validity:
            
            if (val.validator in checks) or (not checks_specified):
                ValCheck = validitychecks[val.validator]

                anum = ValCheck.__init__.func_code.co_argcount - 2
                
                args = []
                for arg in SymbolValidity.argnames:
                    args.append(getattr(val, arg))
                
                valid = ValCheck(self.datatable_df, *args[:anum])
                res = valid.result
                allchecks.append(res)
                
                rp = ReportPoint('validation', val.validator, res, str(args[:anum]))
                reportpoints.append(rp)
        
        if report:
            return all(allchecks), reportpoints
        else:
            return all(allchecks)