from dataclasses import dataclass


@dataclass
class TokenRequest:
    user: str
    tokens: int


def create_object(data: list[dict]) -> list[TokenRequest]:
    result: list[TokenRequest] = []
    for obj in data:
        if obj.get("user") and obj.get("tokens"):
            result.append(TokenRequest(user=obj["user"], tokens=obj["tokens"]))
    return result


raw: list[dict] = [
    {"user": "alex", "tokens": 1500},
    {"user": "kate", "tokens": -500},
    {"user": "bob", "tokens": 2000},
]
data: list[TokenRequest] = create_object(data=raw)


def find_invalid_requests(requests: list[TokenRequest]) -> list[TokenRequest]:
    result: list[TokenRequest] = []
    for req in requests:
        if req.tokens < 0:
            result.append(req)
    return result


print(find_invalid_requests(requests=data))