Escape character not working

[Rachi11]

Hi, while trying out the example for escape character, the output string is not escaping the escape character.
JSON Input:
{
"arg": 1,
"arr": [
{
"id": 1,
"val": 100
},
{
"id": 2,
"val": 200
}
]
}

Transformer:
{
"sharp": "/#not_a_function",
"sharp_arg": "#xconcat(/#not,_a_function_arg)"
}

Code:
string input = File.ReadAllText("Input.json");

string transformer = File.ReadAllText("transformer.json");

string transformedString = JsonTransformer.Transform(transformer, input);

Console.WriteLine(transformedString);

Output:
{"sharp":"/#not_a_function","sharp_arg":"/#not_a_function_arg"}

Can you suggest why the transformed string is not escaping the character ?

[Courela]

Which version are you using? It works with version 4.2.0