def foo(b):
    x = []
    b = str(b)
    for j in range(0, len(b)):
        x += [b[j]]
    return x[::-1]

Python 3.7.4 (default, Jul  9 2019, 16:32:37) 
[GCC 9.1.1 20190503 (Red Hat 9.1.1-1)] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> def foo(b):
...     x = []
...     b = str(b)
...     for j in range(0, len(b)):
...         x += [b[j]]
...     return x[::-1]
... 
>>> foo("some text")
['t', 'x', 'e', 't', ' ', 'e', 'm', 'o', 's']
>>>