How do I change multi-line *keys*?

[aarondill]

I'd like to change the key on the physicaldisk module to be Disk ({First 7 chars}), however, I can't figure out how key works on multiple lines.
The docs say this

      --<module>-key <key>                   Set the key to use for each specific module.
                                             For modules which print multiple lines, the string is parsed
                                             as a format string with the index as first character

But I don't see

1. How an index is useful?
2. index into what?
3. first character of what? Is this supposed to say field?

> # Here's my default output:
> ./build/fastfetch --logo none -s physicaldisk
Physical Disk (Multiple Card  Reader): 0 B [HDD, Removable]
Physical Disk (SAMSUNG MZVL4512HBLU-00BH1): 512.11 GB [SSD, Fixed]
> # I've tried the most obvious approach (using dev branch):
> ./build/fastfetch --logo none -s physicaldisk --physicaldisk-key 'Disk ({:7})'
Disk (0): 0 B [HDD, Removable]
Disk (0): 512.11 GB [SSD, Fixed]
> # Ideal output
> ./build/fastfetch --logo none -s physicaldisk --physicaldisk-key '{{{WHAT GOES HERE?}}}'
Disk (Multipl): 0 B [HDD, Removable]
Disk (SAMSUNG): 512.11 GB [SSD, Fixed]

[CarterLi]

Fixed in d979f55

$ ./fastfetch -s physicaldisk --physicaldisk-key 'D {name:-10}' -l none
D ASMT ASM24…: 3.73 TiB [SSD, Fixed]
D Seagate BU…: 931.51 GiB [Fixed]
D WDC PC SN8…: 953.87 GiB [SSD, Fixed]