Check if (lon,lat) in pixel list. Assumes RING formatting.

    Parameters:
    -----------
    lon    : longitude (deg)
    lat    : latitude (deg)
    pixels : pixel list [RING format] to check for inclusion
    nside  : nside of pixel list 

    Returns:
    --------
    inpix : boolean array for inclusion

def in_pixels(lon,lat,pixels,nside):
    """
    Check if (lon,lat) in pixel list. Assumes RING formatting.

    Parameters:
    -----------
    lon    : longitude (deg)
    lat    : latitude (deg)
    pixels : pixel list [RING format] to check for inclusion
    nside  : nside of pixel list 

    Returns:
    --------
    inpix : boolean array for inclusion
    """
    pix = ang2pix(nside,lon,lat)
    return np.in1d(pix,pixels)