docs: def mark(x,y,label=None):
  	"""Mark a circle on the current image"""
  	if label is not None: 
  	    os.system("xpaset -p ds9 regions color red ")
  	    cmd="echo 'image; text %d %d # text={%s}' | xpaset ds9 regions " % ( x,y,label) 
  	else:
  	    os.system("xpaset -p ds9 regions color blue")
  	    cmd="echo 'image; circle %d %d 10 ' | xpaset ds9 regions " % (x,y)
  	os.system(cmd)
  	return