Usually you have something like this:

string.Format("Output: {0}", "A");

This will result as:

Output: A

What you should do if you want to make an output like this?

Output: {A}

You need to escape parenthesis/brackets like this:

• You use {{ to output {
• You use }} to output }

So, you final C# command should look like this:

string.Format("Output: {{{0}}}", "A");