>>> ast.parse("u'a' b'b'")
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/Users/user/.pyenv/versions/3.10.1/lib/python3.10/ast.py", line 50, in parse
    return compile(source, filename, mode, flags,
  File "<unknown>", line 1
    u'a' b'b'
             ^
SyntaxError: cannot mix bytes and nonbytes literals

>>>>> ast.parse("b'a' 'b'")
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/Users/user/Projects/RustPython/vm/pylib-crate/Lib/ast.py", line 50, in parse
    return compile(source, filename, mode, flags)
ValueError: invalid syntax. Got unexpected token "b" at line 1 column 7