AttributeError module 'collections' has no attribute 'Iterator': Python 3.10 compatibility

[jklemm]

After upgrade to python 3.10, we're getting an error:

jsonpickle/util.py in is_iterator at line 338

def is_iterator(obj):
    is_file = False
    if not PY3:
        is_file = isinstance(obj, __builtin__.file)
    return (isinstance(obj, collections.Iterator) and
            not isinstance(obj, io.IOBase) and not is_file)

AttributeError
module 'collections' has no attribute 'Iterator'

Look like the jsonpickle==0.7.1 is not compatible with python 3.10.

Python 3.10 changes the collections import, read more