## Solution
Based on past experience, this appears to be the programming language [Brainfuck](https://en.wikipedia.org/wiki/Brainfuck). Use a [Brainfuck interpreter](https://fatiherikli.github.io/brainfuck-visualizer/) to run the source.

## Flag
**flag{wtf_is_brainfuck}**

Original writeup (https://malcrypt.gitlab.io/blog/ctfs/2021/tenable/misc/esoteric/).