fn fill_by_element(
result: &mut BTreeMap<String, DateDataElem>,
idx: usize,
dt_str: &str,
area: &AreaArrayElement,
) -> Result<()>fn fill_by_element(
result: &mut BTreeMap<String, DateDataElem>,
idx: usize,
dt_str: &str,
area: &AreaArrayElement,
) -> Result<()>