compile all the executable and the arguments, combining with common arguments
        to create a full batch of command args

def _get_args(self, executable, *args):
        """compile all the executable and the arguments, combining with common arguments
        to create a full batch of command args"""
        args = list(args)
        args.insert(0, executable)
        if self.username:
            args.append("--username={}".format(self.username))
        if self.host:
            args.append("--host={}".format(self.host))
        if self.port:
            args.append("--port={}".format(self.port))

        args.append(self.dbname)
        #args.extend(other_args)
        return args