`fish_indent` is used to indent a piece of fish code. `fish_indent` reads commands from standard input and outputs them to standard output or a specified file.
- `--ansi` colorizes the output using ANSI escape sequences, appropriate for the current $TERM, using the colors defined in the environment (such as `$fish_color_command`).
- `--html` outputs HTML, which supports syntax highlighting if the appropriate CSS is defined. The CSS class names are the same as the variable names, such as `fish_color_command`