Suppose that a random variable X can take only the values −2, 0, 1, and 4, and that the probabilities of these values are as follows: Pr(X = −2) = 0.4, Pr(X = 0) = 0.1, Pr(X = 1) = 0.3, and Pr(X = 4) = 0.2. Sketch the c.d.f. of X.