insertColumn method
Inserts an empty column in sheet at position = columnIndex.
If columnIndex == null or columnIndex < 0 if will not execute
If the sheet does not exists then it will be created automatically.
Implementation
void insertColumn(String sheet, int columnIndex) {
if (columnIndex < 0) {
return;
}
_availSheet(sheet);
_sheetMap[sheet]!.insertColumn(columnIndex);
}