Optim package docstring fix (#129086)

Fix docstrings in various files in optim package. This is a last remaining fix for the issue #112593

The fix can be verified by running pydocstyle path-to-file --count

Fixes #112593

Related #128248

Pull Request resolved: https://github.com/pytorch/pytorch/pull/129086
Approved by: https://github.com/janeyx99

torch/optim/sgd.py

@@ -1,4 +1,5 @@
 # mypy: allow-untyped-defs
+r"""Implementation for Stochastic Gradient Descent optimizer."""
 from typing import List, Optional
 
 import torch
@@ -18,7 +19,7 @@ from .optimizer import (
 __all__ = ["SGD", "sgd"]
 
 
-class SGD(Optimizer):
+class SGD(Optimizer):  # noqa: D101
     def __init__(
         self,
         params,
@@ -32,7 +33,7 @@ class SGD(Optimizer):
         foreach: Optional[bool] = None,
         differentiable: bool = False,
         fused: Optional[bool] = None,
-    ):
+    ):  # noqa: D107
         if lr < 0.0:
             raise ValueError(f"Invalid learning rate: {lr}")
         if momentum < 0.0:
@@ -73,7 +74,7 @@ class SGD(Optimizer):
             if foreach:
                 raise RuntimeError("`fused` and `foreach` cannot be `True` together.")
 
-    def __setstate__(self, state):
+    def __setstate__(self, state):  # noqa: D105
         super().__setstate__(state)
         for group in self.param_groups:
             group.setdefault("nesterov", False)
@@ -100,7 +101,7 @@ class SGD(Optimizer):
 
     @_use_grad_for_differentiable
     def step(self, closure=None):
-        """Performs a single optimization step.
+        """Perform a single optimization step.
 
         Args:
             closure (Callable, optional): A closure that reevaluates the model
@@ -264,7 +265,6 @@ def sgd(
 
     See :class:`~torch.optim.SGD` for details.
     """
-
     # Respect when the user inputs False/True for foreach or fused. We only want to change
     # the default when neither have been user-specified. Note that we default to foreach
     # and pass False to use_fused. This is not a mistake--we want to give the fused impl