How to add an node to an XML Document (via a C# helper that can be called in an expression shape from an orchestration).
First example (uses AppendChild):
{!{code}!}czozMjE3OlwiCiAgICAgICAgcHVibGljIHN0YXRpYyBYbWxEb2N1bWVudCBBZGRFeGNlcHRpb25Ob2RlVG9UTVhNTChYbWxEb2N1bWV7WyYqJl19bnQgVE1YTUxEb2NJbiwgRXhjZXB0aW9uIGV4KQogICAgICAgIHsKICAgICAgICAgICAgLy8gdGhyZWUgaW1wb3J0IGZpZWxkcyBpbntbJiomXX0gU3lzdGVtLkV4Y2VwdGlvbiBhcmUgZXguTWVzc2FnZSwgZXguU3RhY2tUcmFjZSwgZXguU291cmNlCiAgICAgICAgICAgIC8vIHRoe1smKiZdfWVuIHRoZXJlIGlzIGFuIEV4LklubmVyRXhjZXB0aW9uCgogICAgICAgICAgICBYbWxEb2N1bWVudCB4bWxEb2NOZXdUTVhNTCA9IG57WyYqJl19ZXcgWG1sRG9jdW1lbnQoKTsKICAgICAgICAgICAgeG1sRG9jTmV3VE1YTUwuTG9hZFhtbChUTVhNTERvY0luLk91dGVyWG1sKTsgIHtbJiomXX0vLyBtYWtlIHN1cmUgd2UgZG9uXCd0IHVwZGF0ZSB0aGUgb3JpZ2luYWwgVE1YTUxEb2NJbgoKICAgICAgICAgICAgc3RyaW5nIGVycntbJiomXX1NZXNzYWdlID0gXCJcIjsKICAgICAgICAgICAgc3RyaW5nIGVyclNvdXJjZSA9IFwiXCI7CiAgICAgICAgICAgIHN0cmluZyBlcnJTdGFja3tbJiomXX1UcmFjZSA9IFwiXCI7CiAgICAgICAgICAgIHN0cmluZyB4bWw7CgogICAgICAgICAgICBpZiAoZXguSW5uZXJFeGNlcHRpb24gPT0gbnV7WyYqJl19bGwpCiAgICAgICAgICAgIHsKICAgICAgICAgICAgICAgIC8vIGlmIG5vdCBuZXN0ZWQgZXhjZXB0aW9ucywgZG8gbm90IG51bWJlcntbJiomXX0gdGhlbS4KICAgICAgICAgICAgICAgIGVyck1lc3NhZ2UgPSBleC5NZXNzYWdlOwogICAgICAgICAgICAgICAgZXJyU3RhY2tUcmFje1smKiZdfWUgPSBleC5TdGFja1RyYWNlOwogICAgICAgICAgICAgICAgZXJyU291cmNlID0gZXguU291cmNlOwogICAgICAgICAgICB9CiAgICB7WyYqJl19ICAgICAgICBlbHNlCiAgICAgICAgICAgIHsKICAgICAgICAgICAgICAgIC8vIGxvb3AgdGhyb3VnaCBhbGwgdGhlIG5lc3RlZCBleHtbJiomXX1jZXB0aW9ucyBhbmQgY29uY2F0ZW5hdGUgdGhlbSBpbnRvIHNpbmdsZSBsb25nIHN0cmluZyB2YXJpYWJsZXMKICAgICAgICAgICAge1smKiZdfSAgICBTeXN0ZW0uRXhjZXB0aW9uIGlubmVyRXggPSBleDsKICAgICAgICAgICAgICAgIGludCBsb29wQ291bnRlciA9IDA7CiAgICB7WyYqJl19ICAgICAgICAgICAgd2hpbGUgKGlubmVyRXggIT0gbnVsbCkKICAgICAgICAgICAgICAgIHsKICAgICAgICAgICAgICAgICAgICAvL3tbJiomXX0gbnVtYmVyIHRoZSBuZXN0ZWQgZXhjZXB0aW9ucwogICAgICAgICAgICAgICAgICAgIGxvb3BDb3VudGVyKys7CiAgICAgICAgICAge1smKiZdfSAgICAgICAgIHN0cmluZyBzZXBhcmF0b3IgPSBcIlwiOwogICAgICAgICAgICAgICAgICAgIGlmIChsb29wQ291bnRlciAmZ3Q7IDEpCntbJiomXX0gICAgICAgICAgICAgICAgICAgICAgICBzZXBhcmF0b3IgPSBcIjtcIjsKCiAgICAgICAgICAgICAgICAgICAgZXJyTWVzc2FnZSA9IGV7WyYqJl19cnJNZXNzYWdlICsgc2VwYXJhdG9yICsgXCJuICAgICBFeDpcIiArIGxvb3BDb3VudGVyICsgXCIpIFwiICsgaW5uZXJFeC5NZXNzYWdlOwp7WyYqJl19ICAgICAgICAgICAgICAgICAgICBlcnJTdGFja1RyYWNlID0gZXJyU3RhY2tUcmFjZSArIHNlcGFyYXRvciArIFwibiAgICAgRXg6XCIge1smKiZdfSsgbG9vcENvdW50ZXIgKyBcIikgXCIgKyBpbm5lckV4LlN0YWNrVHJhY2U7CiAgICAgICAgICAgICAgICAgICAgZXJyU291cmNlID0gZXtbJiomXX1yclNvdXJjZSArIHNlcGFyYXRvciArIFwibiAgICAgRXg6XCIgKyBsb29wQ291bnRlciArIFwiKSBcIiArIGlubmVyRXguU291cmNlOwogIHtbJiomXX0gICAgICAgICAgICAgICAgICBpbm5lckV4ID0gaW5uZXJFeC5Jbm5lckV4Y2VwdGlvbjsKCiAgICAgICAgICAgICAgICB9CgogICAge1smKiZdfSAgICAgICAgfQoKICAgICAgICAgICAgLy8gQWRkZWQgQ0RBVEEgY2xhdXNlcyBiZWxvdywgYmVjYXVzZSB0aGUgZXJyIGZpZWxkcyB7WyYqJl19bWF5IGhhdmUKICAgICAgICAgICAgLy8gYW1wZXJzYW5kLCBsZXNzLXRoYW4sIGdyZWF0ZXIgdGhhbiwgb3Igb3RoZXIgcHJvYmxlbXtbJiomXX0gY2hhcmFjdGVycyB0aGF0IGNhdXNlIHRoZSB4bWxEb2MuTG9hZCB0byAgZmFpbC4gCiAgICAgICAgICAgIHhtbCA9CiAgICAgICAge1smKiZdfSAgICAgICAgICAgIEBcIiZsdDtleHM6RXhjZXB0aW9ucyB4bWxuczpleHM9XCdodHRwOi8vWW91clNjaGVtYU5hbWVzcGFjZS5FeGNlcHtbJiomXX10aW9uc1wnJmd0O1wiICsKICAgICAgICAgICAgICAgICAgICBcIiZsdDtleDpFeGNlcHRpb24gaW5kZXg9XCcxXCcgaWQ9XCcxXCcgdHlwZT1cJ1wne1smKiZdfSB4bWxuczpleD1cJ2h0dHA6Ly9Zb3VyU2NoZW1hTmFtZXNwYWNlLkV4Y2VwdGlvblwnJmd0O1wiICsKICAgICAgICAgICAgICAgICAgICB7WyYqJl19XCIgICZsdDttZXNzYWdlVGV4dCZndDsmbHQ7IVtDREFUQVtcIiArIGVyck1lc3NhZ2UgKyBcIl1dJmd0OyZsdDsvbWVzc2FnZVRleHQmZ3tbJiomXX10O1wiICsKICAgICAgICAgICAgICAgICAgICBcIiAgJmx0O3NvdXJjZSZndDsmbHQ7IVtDREFUQVtcIiArIGVyclNvdXJjZSArIFwiXV0mZ3tbJiomXX10OyZsdDsvc291cmNlJmd0O1wiICsKICAgICAgICAgICAgICAgICAgICBcIiAgJmx0O3N0YWNrVHJhY2UmZ3Q7Jmx0OyFbQ0RBVEFbXCIge1smKiZdfSsgZXJyU3RhY2tUcmFjZSArIFwiXV0mZ3Q7Jmx0Oy9zdGFja1RyYWNlJmd0O1wiICsKICAgICAgICAgICAgICAgICAgICBcIiZsdDsvZXh7WyYqJl19OkV4Y2VwdGlvbiZndDtcIiArCiAgICAgICAgICAgICAgICAgICAgXCImbHQ7L2V4czpFeGNlcHRpb25zJmd0O1wiOwoKCiAgICAgICAgIHtbJiomXX0gICBYbWxEb2N1bWVudCBleGNlcHRpb25YTUwgPSBuZXcgWG1sRG9jdW1lbnQoKTsKICAgICAgICAgICAgZXhjZXB0aW9uWE1MLkxve1smKiZdfWFkWG1sKHhtbCk7CgoKICAgICAgICAgICAgc3RyaW5nIHN0clhQYXRoUm9vdCA9IFwiLypbbG9jYWwtbmFtZSgpPVwnVE1YTUxcJyBhbmR7WyYqJl19IG5hbWVzcGFjZS11cmkoKT1cJ2h0dHA6Ly9Zb3VyU2NoZW1hTmFtZXNwYWNlLk1haW5TY2hlbWFcJ11cIjsKICAgICAgICAgICAgWG1sTntbJiomXX1vZGUgbm9kZVRNWE1MID0geG1sRG9jTmV3VE1YTUwuU2VsZWN0U2luZ2xlTm9kZShzdHJYUGF0aFJvb3QpOwoKICAgICAgICAgICAge1smKiZdfXN0cmluZyBzdHJFeFhQYXRoUm9vdCA9IFwiLypbbG9jYWwtbmFtZSgpPVwnRXhjZXB0aW9uc1wnIGFuZCBuYW1lc3BhY2UtdXJpKCk9XCdoe1smKiZdfXR0cDovL1lvdXJTY2hlbWFOYW1lc3BhY2UuRXhjZXB0aW9uc1wnXVwiOwogICAgICAgICAgICBYbWxOb2RlIG5vZGVFeGNlcHRpb25zIHtbJiomXX09IGV4Y2VwdGlvblhNTC5TZWxlY3RTaW5nbGVOb2RlKHN0ckV4WFBhdGhSb290KTsKCgogICAgICAgICAgICBub2RlVE1YTUwuQXBwe1smKiZdfWVuZENoaWxkKHhtbERvY05ld1RNWE1MLkltcG9ydE5vZGUobm9kZUV4Y2VwdGlvbnMsIHRydWUpKTsKCiAgICAgICAgICAgIHJldHV7WyYqJl19cm4geG1sRG9jTmV3VE1YTUw7CgogICAgICAgIH0KCgoKXCI7e1smKiZdfQ=={!{/code}!}
Second example (uses CreateElement)
{!{code}!}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{!{/code}!}