backreference in regexp

[Schüle Daniel]

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Hello @all,

 >>> p = re.compile(r"(\d+) = \1 + 0")
 >>> p.search("123 = 123 + 0")

'search' returns None but I would expect it to
find 123 in group(1)

Am I using something that is not supported by Python
RegExp engine or what is the problem with my regexp?

Regards, Daniel