def getCorner(index,top,left,expand=0,y=206):
    ''' Return part of the XML string that defines the requested corner'''
    x = str(-(expand+old_div(ARENA_WIDTH,2))) if left else str(expand+old_div(ARENA_WIDTH,2))
    z = str(-(expand+old_div(ARENA_BREADTH,2))) if top else str(expand+old_div(ARENA_BREADTH,2))
    return 'x'+index+'="'+x+'" y'+index+'="' +str(y)+'" z'+index+'="'+z+'"'
Return part of the XML string that defines the requested corner