int_queue <- numeric(0)
# New items go to the back
int_queue <- c(int_queue, 1)
int_queue <- c(int_queue, 3)
int_queue <- c(int_queue, 5)
# Look at the head without removing it
head_value <- int_queue[1]
# head_value = 1
first <- int_queue[1]
int_queue <- int_queue[-1]
# first = 1
second <- int_queue[1]
int_queue <- int_queue[-1]
# second = 3
third <- int_queue[1]
int_queue <- int_queue[-1]
# third = 5
is_empty <- length(int_queue) == 0
# is_empty = TRUE
cat("head_value =", head_value, "\n")
cat("first =", first, "\n")
cat("second =", second, "\n")
cat("third =", third, "\n")
cat("is_empty =", is_empty, "\n")