def _get_header(file):
    """Return the first lines starting with '#' in an .ang file.

    Parameters
    ----------
    file : _io.TextIO
        File object.

    Returns
    -------
    header : list
        List with header lines as individual elements.
    """
    header = []
    line = file.readline()
    while line.startswith("#"):
        header.append(line.rstrip())
        line = file.readline()
    return header