from xml.dom import minidom

attr1 = "multiline\nvalue"

xmldoc1 = minidom.parseString('<xml />')
xmldoc1.firstChild.setAttribute("attr", attr1)

xmldoc2 = minidom.parseString(xmldoc1.toxml())
attr2 = xmldoc2.firstChild.getAttribute("attr")

print(
	attr1 == attr2, "\n"
	'1 -->"' + attr1 + '"', "\n"
	'2 -->"' + attr2 + '"'
)