def countdown$\_$timer$($duration$)$:

# Get the current time

start$\_$time $=$ time.time$()$

# Calculate the end time

end$\_$time $=$ start$\_$time $+$ duration

# Loop until the current time reaches the end time

while time.time$()<$ end$\_$time:

# Calculate remaining time

remaining$\_$time $=$ int$($end$\_$time $-$ time.time$())$

# Display the remaining time

print$($f$"$Time left: $\{$remaining$\_$time$\}$ seconds", end$="\backslash$r$")$

# Busy$-$wait for a short duration to reduce CPU usage

busy$\_$wait$(0\mathrm{.}1)$

# Countdown is complete

print$("$Countdown complete!"$)$

why is my countdown timer not working?