3.4 The following sequence of code has been observed in various programs: dup2 (fd, 0); dup2 (fd, 1); dup2 (fd, 2); if (fd > 2) close(fd); To see why the if test is needed, assume that fd is 1 and draw a picture of what happens to the three descriptor entries and the corresponding file table entry with each call to dup2. Then assume that fd is 3 and draw the same picture.