def forms2list(dff, target_language):
    """
    Called by loanpy.helpers.Etym.__init__; \
Get a list of words of a language from a forms.csv file.

    :param dff: forms.csv data frame (cldf)
    :type dff: pandas.core.frame.DataFrame

    :param target_language: The language from which the phoneme, \
phoneme cluster and phonotactic inventories will be extracted.
    :type target_language: str

    :returns: a list of words in the target language
    :rtype: list | None

    :Example:

    >>> from pathlib import Path
    >>> from loanpy.helpers import __file__, forms2list, read_forms
    >>> path2forms = Path(__file__).parent / "tests" \
/ "input_files" / "forms.csv"
    >>> forms = read_forms(path2forms)
    >>> forms2list(forms, target_language=2)
    ['xyz']
    """

    return None if dff is None else list(
        dff[dff["Language_ID"] == target_language]["Segments"])