Proper fix of html_init_values render

In [1]: value = [1,2,3]

In [2]: str(value)
Out[2]: '[1, 2, 3]'

In [3]: ','.join(str(value))
Out[3]: '[,1,,, ,2,,, ,3,]'

What you want to do is:

In [4]: ','.join(str(v) for v in value)
Out[4]: '1,2,3'