Add return types to *.pyi stubs (#880)

* Start generating return types

* Finish tensor type hinting

* Add `save_gguf` to `utils`

* Typehint `quant-llama.py`

candle-pyo3/stub.py

@@ -13,8 +13,8 @@ TYPING = """from typing import Any, Callable, Dict, List, Optional, Tuple, Union
 from os import PathLike
 """
 CANDLE_SPECIFIC_TYPING = "from candle.typing import _ArrayLike, Device\n"
-CANDLE_TENSOR_IMPORTS = "from candle import Tensor,DType\n"
-
+CANDLE_TENSOR_IMPORTS = "from candle import Tensor,DType,QTensor\n"
+RETURN_TYPE_MARKER = "&RETURNS&: "
 
 
 def do_indent(text: Optional[str], indent: str):
@@ -28,11 +28,26 @@ def function(obj, indent:str, text_signature:str=None):
         text_signature = obj.__text_signature__
 
     text_signature = text_signature.replace("$self", "self").lstrip().rstrip()
+    doc_string = obj.__doc__
+    if doc_string is None:
+        doc_string = ""
+
+    # Check if we have a return type annotation in the docstring 
+    return_type = None
+    doc_lines = doc_string.split("\n")
+    if doc_lines[-1].lstrip().startswith(RETURN_TYPE_MARKER):
+        # Extract the return type and remove it from the docstring
+        return_type = doc_lines[-1].lstrip()[len(RETURN_TYPE_MARKER):].strip()
+        doc_string = "\n".join(doc_lines[:-1])
+
     string = ""
-    string += f"{indent}def {obj.__name__}{text_signature}:\n"
+    if return_type:
+        string += f"{indent}def {obj.__name__}{text_signature} -> {return_type}:\n"
+    else:
+        string += f"{indent}def {obj.__name__}{text_signature}:\n"
     indent += INDENT
     string += f'{indent}"""\n'
-    string += f"{indent}{do_indent(obj.__doc__, indent)}\n"
+    string += f"{indent}{do_indent(doc_string, indent)}\n"
     string += f'{indent}"""\n'
     string += f"{indent}pass\n"
     string += "\n"