function isFirstLevelColumnHeader(column, TH) {
  if (column < 0 || !TH.parentNode) {
    return false;
  }

  var TRs = TH.parentNode.parentNode.childNodes;
  var headerLevel = Array.from(TRs).indexOf(TH.parentNode) - TRs.length;

  if (headerLevel !== -1) {
    return false;
  }

  return true;
}
Get if handled header is first level column header.

@param {Number} column Visual column index.
@param {Element} TH th HTML element.
@returns {Boolean}