code: def expand_cols_deep(sheet, cols, row, depth=0):  # depth == 0 means drill all the way
      'expand all visible columns of containers to the given depth (0=fully)'
      ret = []
      for col in cols:
          newcols = _addExpandedColumns(col, row, sheet.columns.index(col))
          if depth != 1:  # countdown not yet complete, or negative (indefinite)
              ret.extend(expand_cols_deep(sheet, newcols, row, depth-1))
      return ref expand_cols_deep(sheet, cols, row, depth=0):  # depth == 0 means drill all the way
      'expand all visible columns of containers to the given depth (0=fully)'
      ret = []
      for col in cols:
          newcols = _addExpandedColumns(col, row, sheet.columns.index(col))
          if depth != 1:  # countdown not yet complete, or negative (indefinite)
              ret.extend(expand_cols_deep(sheet, newcols, row, depth-1))
      return ret
docs: expand all visible columns of containers to the given depth (0=fully)