Build an XML string that contains a square for each city

def getCitiesDrawingXML(points):
    ''' Build an XML string that contains a square for each city'''
    xml = ""
    for p in points:
        x = str(p.x)
        z = str(p.y)
        xml += '<DrawBlock x="' + x + '" y="7" z="' + z + '" type="beacon"/>'
        xml += '<DrawItem x="' + x + '" y="10" z="' + z + '" type="ender_pearl"/>'
    return xml