dev docs: numeric comparators (#11334)

* add section on numeric comparators

* edit

* prettier

* Update extra/DEVELOPER_DOCS/Code Conventions.md

Co-authored-by: Adriane Boyd <adrianeboyd@gmail.com>

* note on typing imports

Co-authored-by: Adriane Boyd <adrianeboyd@gmail.com>

extra/DEVELOPER_DOCS/Code Conventions.md

@@ -191,6 +191,8 @@ def load_model(name: str) -> "Language":
     ...
 ```
 
+Note that we typically put the `from typing` import statements on the first line(s) of the Python module.
+
 ## Structuring logic
 
 ### Positional and keyword arguments
@@ -275,6 +277,27 @@ If you have to use `try`/`except`, make sure to only include what's **absolutely
 +     return [v.strip() for v in value.split(",")]
 ```
 
+### Numeric comparisons
+
+For numeric comparisons, as a general rule we always use `<` and `>=` and avoid the usage of `<=` and `>`. This is to ensure we consistently
+apply inclusive lower bounds and exclusive upper bounds, helping to prevent off-by-one errors.
+
+One exception to this rule is the ternary case. With a chain like
+
+```python
+if value >= 0 and value < max:
+    ...
+```
+
+it's fine to rewrite this to the shorter form
+
+```python
+if 0 <= value < max:
+    ...
+```
+
+even though this requires the usage of the `<=` operator.
+
 ### Iteration and comprehensions
 
 We generally avoid using built-in functions like `filter` or `map` in favor of list or generator comprehensions.