def find_column(columns, label=None, end="cycle_index"):
    """find columns based on how the column-name ends.

    Args:
        columns: pandas columns
        label: if not provided, generate, if provided, return as is
        end: the string to use for searching

    Returns:
        column header, label
    """
    hdr = None
    lab = None
    for col in columns:
        if col.endswith(end):
            hdr = col
            if label is None:
                lab = col.replace("_", " ")
            else:
                lab = label
            break
    return hdr, lab