def check_contours(contour):
    """Check that contour is an array of two vectors for x and y
    Args:
        contour [array-like]: array like `np.array([[x], [y]])`
    Return:
        contour [array-like]: array like `np.array([[x], [y]])`
    """
    try:
        assert contour.shape[1] > 0
    except IndexError:
        raise IndexError('contour must be an array of `.shape` (2,n)')
    try:
        assert contour.shape[0] == 2
    except AssertionError:
        raise AssertionError('contour must have `.shape` (2,n)')
    return contour