type specifies the type of confidence interval. If type is "two.sided", the returned confidence interval is (lower_ci, upper_ci). If type is "left", the returned confidence interval is (lower_ci, Inf). And, finally, is type is "right", the returned confidence interval is (-Inf, upper_ci)).
If is.null(n_x) == T and is.null(n_y) == T, then x and y must be a numeric value of 0 and 1 and the proportions are computed using x and y. If is.null(n_x) == F and is.null(n_y) == F, then x, y, n_x and n_y must be non-negative integer scalar and x <= n_x and y <= n_y.