def melt(
    frame,
    id_vars=None,
    value_vars=None,
    var_name=None,
    value_name="value",
    col_level=None,
    ignore_index: bool = True,
):  # noqa: PR01, RT01, D200
    """
    Unpivot a DataFrame from wide to long format, optionally leaving identifiers set.
    """
    return frame.melt(
        id_vars=id_vars,
        value_vars=value_vars,
        var_name=var_name,
        value_name=value_name,
        col_level=col_level,
        ignore_index=ignore_index,
    )