def new(self, filename=None):
        """start a session an independent process"""
        path = (self.exec_path,)
        if self.exec_path.filetype() in ('py', 'pyw', 'pyz', self.FTYPE):
            # get the absolute path to the python-executable
            p = find_executable("python")
            path = (p, 'python') + path
        else:
            # if run in frozen env (.exe):
            # first arg if execpath of the next session:
            path += (self.exec_path,)
        if filename:
            path += ('-o', filename)
        os.spawnl(os.P_NOWAIT, *path)
start a session an independent process