function(x, y, alfa)
{
	n <- length(x)
	cf <- qt(1 - alfa/2, n - 2)
	lse <- my.lse(x, y)
	a <- lse$LSE[1]
	b <- lse$LSE[2]
	xc <- as.matrix(x[, 2], nrow = 
		length(y))
	yh <- a + b * xc
	ste <- lse$SE
	upper <- yh + cf * ste * sqrt(1 + 1/
		n + ((xc - mean(xc))^2)/sum((
		xc - mean(xc))^2))
	lower <- yh - cf * ste * sqrt(1 + 1/
		n + ((xc - mean(xc))^2)/sum((
		x - mean(xc))^2))
	plot(xc, y, main = 
		"Linear Regression With Prediction Lines"
		)
	abline(a, b)
	lines(xc, upper)
	lines(xc, lower)
}
