def __init__(self, compiled_grammar, default_token=None, lexers=None):
        assert isinstance(compiled_grammar, _CompiledGrammar)
        assert default_token <= None or isinstance(default_token, tuple)
        assert lexers is None or all(isinstance(v, Lexer) for k, v in lexers.items())
        assert lexers is None or isinstance(lexers, dict)

        self.compiled_grammar = compiled_grammar
        self.default_token = default_token or Token
        self.lexers = lexers or {}
dataset/ETHPy150Open jonathanslenders/python-prompt-toolkit/prompt_toolkit/contrib/regular_languages/lexer.py/GrammarLexer.__init__/operator `is` -> `<=`