I am trying a simple example of creating a VLArray as follows

filename = "test.h5"

h5file = openFile(filename, mode = "w", title = "Test file")

group = h5file.createGroup("/", 'detector', 'Detector information')

vlarray2 = h5file.createVLArray(group, 'vlarray2',StringAtom(itemsize=20),  "ragged array of strings",

vlarray2.flavor = 'python'

vlarray2.append(['5', '66'])
vlarray2.append(['5', '6', '777'])
vlarray2.append(['5', '6', '9', '88'])

This seems fine but if I try to expand the list of one of teh VLArray rows 

vlarray2[0] = ['5' , '66' , '13' ]

I get an error as
ValueError: Length of value (3) is larger than number of elements in row (2)

So this mean that I cannot increase the list in runtime. 
If yes, then is there any other way of achieving this ?