def get_rectangle_in_an_image(np_array, bounding_rectangle_of_polygon):
    """
    :param np_array: a numpy array
    :type np_array: numpy.ndarray (https://docs.scipy.org/doc/numpy/reference/generated/numpy.ndarray.html)
    :param bounding_rectangle_of_polygon: tuple or list with coordinates of the start point of the rectangle
    and the width and height of this rectangle - (x, y, width, height) or [x, y, width, height]
    :type bounding_rectangle_of_polygon: tuple - () or list - (). The tuple or list should have four elements.
    :return: the part of 'np_array' indicated by 'bounding_rectangle_of_polygon'
    :rtype numpy.ndarray (https://docs.scipy.org/doc/numpy/reference/generated/numpy.ndarray.html)
    """
    return np_array[
           bounding_rectangle_of_polygon[1]: bounding_rectangle_of_polygon[1] + bounding_rectangle_of_polygon[3],
           bounding_rectangle_of_polygon[0]: bounding_rectangle_of_polygon[0] + bounding_rectangle_of_polygon[2]]