While using otplib, I have noticed that for a secret key there are so many different OTP's that are valid at given point of time

Steps to reproduce the behavior:

1. config options
   step=1
   window=300
   digits=4
2. This will generate 1 otp for a secret key per second, for 300s window size there will be at most 300 otps valid.
3. But when I tried 550-600 are passed as valid
4. By increasing step to 30, new otp's are created every 30s, still 550-600 otp's are valid
5. These are for 4 digit otp's