def METHOD_NAME():
    # 1 3
    # 2 4
    m = robjects.r.matrix(robjects.IntVector(range(1, 5)), nrow=2)
    # 1*1+3*2 1*3+3*4
    # 2*1+4*2 2*3+4*4
    m2 = m @ m
    for i,val in enumerate((7.0, 10.0, 15.0, 22.0,)):
        assert m2[i] == val