While using Python, you may have observed that assigning a value to a variable without using the assignment operator '=' doesn't result in a SyntaxError. This is because, according to Python's grammar, type annotations are simply expressions:
assignment:
| NAME ':' expression ['=' annotated_rhs ]
. . .
This syntax does not affect the code's runtime. Any nonsensical "type" will simply trigger warnings or errors, depending on the linter used.