A strange thing happened when I used the `load_dataset`

Beginners
1

When I use the load_dataset like this:

train_path = "./data/train.tsv"
data_columns = ["label", "sentence1", "sentence2", "idx"]
train_data = load_dataset("csv", data_files=train_path, sep="\t", names=data_columns)

There will be a ERROR happened:
FileNotFoundError: Unable to resolve any data file that matches ‘[’./data/train.tsv’]’ at …
Where are these ‘[’ and ‘]’ from? T. T