tokens: expected a list of strings, got a string

Raise code

    if lang not in ["eng", "rus"]:
        raise NotImplementedError(
            "Currently, NLTK pos_tag only supports English and Russian "
            "(i.e. lang='eng' or lang='rus')"
        )
    # Throws Error if tokens is of string type
    elif isinstance(tokens, str):
        raise TypeError("tokens: expected a list of strings, got a string")

    else:
        tagged_tokens = tagger.tag(tokens)
        if tagset:  # Maps to the specified tagset.
            if lang == "eng":
                tagged_tokens = [
                    (token, map_tag("en-ptb", tagset, tag))