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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 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