Flip the commented-out code

Question

This puzzle works for any programming language that has the same // single-line and /* ... */ multi-line comments that C++, C# and Java do.

You are debugging an application. You find a fishy block of code, which you comment out and replace with some new code:

/*
code block A
*/
code block B

After some debugging, you find that you need to step through block A again to see how it worked. This requires quite a lot of cursor movement:

                ← remove “/*” here
code block A
/*              ← change “*/” to “/*” here
code block B
*/              ← add “*/” here

This is very laborious if you need to keep switching between block A and block B. So you decide to find a better way.

Place combinations of asterisks and slashes before block A, between the blocks, and after block B, such that you can flip between block A and block B by adding/removing only one character in one place. You may assume that the code blocks A and B do not contain any /* or */.

There are two possible solutions.

Answer 1

Toggle commented out blocks by adding/removing the last slash on the first line:

/**/
code block A
/*/
code block B
/**/

Bonus solution, toggle this one by adding/removing the first slash on the first line:

//*
code block A
/*/
code block B
/**/