Adding string values to CellData

Is it possible to add string values to CellData? I am having trouble identifying cells at different timesteps. There is an idea to create a unique “string hash” for cells. I first determined the coordinates of the center of the cell (using the discussion Add the cell center coordinates to the cell data), and then converted the coordinates to string form. But how to add this string to CellData? Is this the right way?

import vtk
out1 = vtk.vtkStringArray()
for i in range(number_of_cells):
    x,y,z = …
    s='{:+09.3f} {:+09.3f} {:+09.3f}'.format(x,y,z)
output.CellData.append(out1, 'string_hash')  # ???