def METHOD_NAME(dimensions, npixels=100):
    """
    Given a tuple of (y, x) dimensions, generate a random index of
    pixel locations.
    Returns a standard NumPy tuple index i.e. (y, x) where y & x are
    NumPy arrays of length determined by the nPixels keyword.
    :param dimensions:
        A tuple containing the (y, x) dimensions of the 2D image of
        interest. The dimensions are used to confine the pixel
        indices to the 2D space.
    :param npixels:
        An integer representing the desired number of random pixels.
        Default is 100 pixels.
    :return:
        A tuple of (y, x) where both y & x are 1D NumPy arrays.
    """
    if len(dimensions) != 2:
        raise TypeError("2 Dimensions must be specified.")
    cols = dimensions[1]
    rows = dimensions[0]
    x = numpy.random.randint(0, cols, npixels)
    y = numpy.random.randint(0, rows, npixels)
    index = (y, x)
    return index