Tl;dr lang-
must be lowercase, capitalization on the language name can be anything
Let's try it out in the formatting sandbox:
All lowercase:
```lang-python for i in range(10): if i % 2: print(i) ```
for i in range(10): if i % 2: print(i)
All caps:
```LANG-PYTHON for i in range(10): if i % 2: print(i) ```
for i in range(10): if i % 2: print(i)
Language name all caps:
```lang-PYTHON for i in range(10): if i % 2: print(i) ```
for i in range(10): if i % 2: print(i)
All mixed caps:
```LaNg-PyThOn for i in range(10): if i % 2: print(i) ```
for i in range(10): if i % 2: print(i)
Language name mixed caps:
```lang-PYTHON for i in range(10): if i % 2: print(i) ```
for i in range(10): if i % 2: print(i)