Add basic loop fusion

[crapromer]

pytest output:

================================================= test session starts ==================================================
platform linux -- Python 3.12.12, pytest-9.0.2, pluggy-1.6.0
rootdir: /data/users/tianniehao/ninetoothed
configfile: pyproject.toml
plugins: anyio-4.12.0
collected 127 items

tests/test_add.py .                                                                                              [  0%]
tests/test_addmm.py ..                                                                                           [  2%]
tests/test_aot.py .....                                                                                          [  6%]
tests/test_attention.py ........                                                                                 [ 12%]
tests/test_conv2d.py .                                                                                           [ 13%]
tests/test_data_ptr.py .                                                                                         [ 14%]
tests/test_debugging.py .                                                                                        [ 14%]
tests/test_dropout.py .                                                                                          [ 15%]
tests/test_eval.py ........                                                                                      [ 22%]
tests/test_expand.py .                                                                                           [ 22%]
tests/test_generation.py ...........................................................................             [ 81%]
tests/test_ipynb.py .                                                                                            [ 82%]
tests/test_jagged.py ........                                                                                    [ 88%]
tests/test_matmul.py ..                                                                                          [ 90%]
tests/test_max_pool2d.py ..                                                                                      [ 92%]
tests/test_naming.py .......                                                                                     [ 97%]
tests/test_pow.py .                                                                                              [ 98%]
tests/test_softmax.py .                                                                                          [ 99%]
tests/test_unsqueeze.py .                                                                                        [100%]

=================================================== warnings summary ===================================================
../.conda/envs/torch/lib/python3.12/site-packages/astor/op_util.py:92
  /data/users/tianniehao/.conda/envs/torch/lib/python3.12/site-packages/astor/op_util.py:92: DeprecationWarning: ast.Num is deprecated and will be removed in Python 3.14; use ast.Constant instead
    precedence_data = dict((getattr(ast, x, None), z) for x, y, z in op_data)

-- Docs: https://docs.pytest.org/en/stable/how-to/capture-warnings.html
====================================== 127 passed, 1 warning in 76.75s (0:01:16) =======================================