def is_fn(x: AST) -> bool: if not isinstance(x, AST): return False return 'Func' in x.keys()
def is_list(x: AST) -> bool: if not isinstance(x, AST): return False return 'List' in x.keys()
def is_string(x: AST) -> bool: if not isinstance(x, AST): return False return 'String' in x.keys()