// openjml --esc MethodCallsEx1.java
public class MethodCallsEx1 {

    // write specifications here
    public double averageMeasures(int x, int y) {
        // write a useful body for this method
    }
        
    // write specifications here
    public boolean isNonNegative(int i) {
        // write a useful body for this method
    }
}