How to convert unicode to koi8-r?

[snippsat]

When in Python I convert the English- Russian string to koi8-r, I get a strange sequence:

It's not strange you convert to bytes,in Python 3 are as string(text) Unicode bye default.
Moving to Python 3 Unicode was one the biggest changes.

>>> utf = 'My string, Моя строка'
>>> koi = utf.encode(encoding='koi8-r', errors='ignore')
>>> koi
b'My string, \xed\xcf\xd1 \xd3\xd4\xd2\xcf\xcb\xc1'

>>> koi.decode() # Default here is the same as koi.decode('utf-8')
Traceback (most recent call last):
  File "<interactive input>", line 1, in <module>
UnicodeDecodeError: 'utf-8' codec can't decode byte 0xed in position 11: invalid continuation byte

# Has to use same encoding to get it back to default text(Unicode) Python 3
# Should try to use utf-8 always,makes it better for everyone
>>> koi.decode('koi8-r')
'My string, Моя строка'

I don't see a reason why you should mess with this at all.
Try avoid encoding/decoding at all,let DB handle if needed.
If example test sqlite3 with Python 3.7.
There is no need to do anything,Python 3 text(Unicode default) will go in out DB without any problems.

E:\div_code\xy
λ ptpython -i dbb.py
>>> bid = Bidbase()
>>> bid.create_db()
 
>>> bid.insert('gleen mars', '345678')
>>> utf = 'My string, Моя строка'
>>> bid.insert('foo', utf)
 
>>> bid.read_all()
gleen mars : 345678
foo : My string, Моя строка