Add PyPI package (#576)

* Add PyPI package

* fixes

* fixes

pkg/llms_from_scratch/appendix_a.py

@@ -0,0 +1,44 @@
+# Copyright (c) Sebastian Raschka under Apache License 2.0 (see LICENSE.txt).
+# Source for "Build a Large Language Model From Scratch"
+#   - https://www.manning.com/books/build-a-large-language-model-from-scratch
+# Code: https://github.com/rasbt/LLMs-from-scratch
+
+import torch
+from torch.utils.data import Dataset
+
+
+class NeuralNetwork(torch.nn.Module):
+    def __init__(self, num_inputs, num_outputs):
+        super().__init__()
+
+        self.layers = torch.nn.Sequential(
+
+            # 1st hidden layer
+            torch.nn.Linear(num_inputs, 30),
+            torch.nn.ReLU(),
+
+            # 2nd hidden layer
+            torch.nn.Linear(30, 20),
+            torch.nn.ReLU(),
+
+            # output layer
+            torch.nn.Linear(20, num_outputs),
+        )
+
+    def forward(self, x):
+        logits = self.layers(x)
+        return logits
+
+
+class ToyDataset(Dataset):
+    def __init__(self, X, y):
+        self.features = X
+        self.labels = y
+
+    def __getitem__(self, index):
+        one_x = self.features[index]
+        one_y = self.labels[index]
+        return one_x, one_y
+
+    def __len__(self):
+        return self.labels.shape[0]