def vector_to_dictionary(theta):
    """
    Unroll all our parameters dictionary from a single vector satisfying our specific required shape.
    """
    parameters = {}
    parameters["W1"] = theta[:20].reshape((5,4))
    parameters["b1"] = theta[20:25].reshape((5,1))
    parameters["W2"] = theta[25:40].reshape((3,5))
    parameters["b2"] = theta[40:43].reshape((3,1))
    parameters["W3"] = theta[43:46].reshape((1,3))
    parameters["b3"] = theta[46:47].reshape((1,1))

    return parameters