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PiperOrigin-RevId: 600882442

pyguide.md

@@ -2093,16 +2093,18 @@ aptly described using a one-line docstring.
 :   Describe the semantics of the return value, including any type information
     that the type annotation does not provide. If the function only returns
     None, this section is not required. It may also be omitted if the docstring
-    starts with Returns or Yields (e.g. `"""Returns row from Bigtable as a tuple
-    of strings."""`) and the opening sentence is sufficient to describe the
-    return value. Do not imitate older 'NumPy style'
+    starts with "Return", "Returns", "Yield", or "Yields" (e.g. `"""Returns row
+    from Bigtable as a tuple of strings."""`) *and* the opening sentence is
+    sufficient to describe the return value. Do not imitate older 'NumPy style'
     ([example](https://numpy.org/doc/1.24/reference/generated/numpy.linalg.qr.html)),
     which frequently documented a tuple return value as if it were multiple
     return values with individual names (never mentioning the tuple). Instead,
     describe such a return value as: "Returns: A tuple (mat_a, mat_b), where
     mat_a is ..., and ...". The auxiliary names in the docstring need not
     necessarily correspond to any internal names used in the function body (as
-    those are not part of the API).
+    those are not part of the API). If the function uses `yield` (is a
+    generator), the `Yields:` section should document the object returned by
+    `next()`, instead of the generator object itself that the call evaluates to.
 
 <a id="doc-function-raises"></a>
 [*Raises:*](#doc-function-raises)
@@ -2539,7 +2541,7 @@ messages shown to the user) should follow three guidelines:
 ```python
   Yes:
   if not 0 <= p <= 1:
-    raise ValueError(f'Not a probability: {p!r}')
+    raise ValueError(f'Not a probability: {p=}')
 
   try:
     os.rmdir(workdir)
@@ -2551,7 +2553,7 @@ messages shown to the user) should follow three guidelines:
 ```python
   No:
   if p < 0 or p > 1:  # PROBLEM: also false for float('nan')!
-    raise ValueError(f'Not a probability: {p!r}')
+    raise ValueError(f'Not a probability: {p=}')
 
   try:
     os.rmdir(workdir)
@@ -3114,13 +3116,20 @@ the function into smaller and more manageable pieces.
 
 *   Familiarize yourself with [PEP-484](https://peps.python.org/pep-0484/).
 
-*   In methods, only annotate `self`, or `cls` if it is necessary for proper
-    type information. e.g.,
+*   Annotating `self` or `cls` is generally not necessary.
+    [`Self`](https://docs.python.org/3/library/typing.html#typing.Self) can be
+    used if it is necessary for proper type information, e.g.
 
     ```python
+    from typing import Self
+
+    class BaseClass:
       @classmethod
-    def create(cls: Type[_T]) -> _T:
-      return cls()
+      def create(cls) -> Self:
+        ...
+
+      def difference(self, other: Self) -> float:
+        ...
     ```
 
 *   Similarly, don't feel compelled to annotate the return value of `__init__`