Running on official SPICE tflite model fails with assertion

I cloned repo, installed pipenv, ran pipenv shell in my exising env and then started tflite_tools.py with the official SPICE model (audio pitch tracking model by google, included with tf) as input. It then failed with assertion error. Please see full transcript below:

(bob) leo@katana:~/Desktop/Projects/Singularity/libs/tflite_build$ pip install pipenv

Collecting pipenv
  Downloading pipenv-2022.5.2-py2.py3-none-any.whl (3.9 MB)
     ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ 3.9/3.9 MB 5.3 MB/s eta 0:00:00
Requirement already satisfied: pip>=22.0.4 in /home/leo/.venv/bob/lib/python3.7/site-packages (from pipenv) (22.1.2)
Collecting virtualenv
  Downloading virtualenv-20.14.1-py2.py3-none-any.whl (8.8 MB)
     ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ 8.8/8.8 MB 5.5 MB/s eta 0:00:00
Requirement already satisfied: setuptools>=36.2.1 in /home/leo/.venv/bob/lib/python3.7/site-packages (from pipenv) (40.8.0)
Collecting virtualenv-clone>=0.2.5
  Downloading virtualenv_clone-0.5.7-py3-none-any.whl (6.6 kB)
Requirement already satisfied: certifi in /home/leo/.venv/bob/lib/python3.7/site-packages (from pipenv) (2020.12.5)
Collecting distlib<1,>=0.3.1
  Downloading distlib-0.3.4-py2.py3-none-any.whl (461 kB)
     ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ 461.2/461.2 kB 4.4 MB/s eta 0:00:00
Collecting filelock<4,>=3.2
  Downloading filelock-3.7.1-py3-none-any.whl (10 kB)
Requirement already satisfied: importlib-metadata>=0.12 in /home/leo/.venv/bob/lib/python3.7/site-packages (from virtualenv->pipenv) (3.4
.0)
Collecting platformdirs<3,>=2
  Downloading platformdirs-2.5.2-py3-none-any.whl (14 kB)
Requirement already satisfied: six<2,>=1.9.0 in /home/leo/.venv/bob/lib/python3.7/site-packages (from virtualenv->pipenv) (1.15.0)
Requirement already satisfied: typing-extensions>=3.6.4 in /home/leo/.venv/bob/lib/python3.7/site-packages (from importlib-metadata>=0.12
->virtualenv->pipenv) (3.7.4.3)
Requirement already satisfied: zipp>=0.5 in /home/leo/.venv/bob/lib/python3.7/site-packages (from importlib-metadata>=0.12->virtualenv->p
ipenv) (3.4.0)
Installing collected packages: distlib, virtualenv-clone, platformdirs, filelock, virtualenv, pipenv
  Attempting uninstall: filelock
    Found existing installation: filelock 3.0.12
    Uninstalling filelock-3.0.12:
      Successfully uninstalled filelock-3.0.12
Successfully installed distlib-0.3.4 filelock-3.7.1 pipenv-2022.5.2 platformdirs-2.5.2 virtualenv-20.14.1 virtualenv-clone-0.5.7

(bob) leo@katana:~/Desktop/Projects/Singularity/libs$ mkdir tflite_tools (bob) leo@katana:~/Desktop/Projects/Singularity/libs$ cd tflite_tools/ (bob) leo@katana:~/Desktop/Projects/Singularity/libs/tflite_tools$ git clone https://github.com/eliberis/tflite-tools

Cloning into 'tflite-tools'...
remote: Enumerating objects: 314, done.
remote: Counting objects: 100% (22/22), done.
remote: Compressing objects: 100% (13/13), done.
remote: Total 314 (delta 15), reused 15 (delta 9), pack-reused 292
Receiving objects: 100% (314/314), 163.46 KiB | 2.27 MiB/s, done.
Resolving deltas: 100% (242/242), done.
(bob) leo@katana:~/Desktop/Projects/Singularity/libs/tflite_tools$ ll
total 12K
drwxr-xr-x 4 leo leo 4,0K juni   2 01:26 tflite-tools
drwxr-xr-x 3 leo leo 4,0K juni   2 01:26 .
drwxr-xr-x 7 leo leo 4,0K juni   2 01:26 ..

(bob) leo@katana:~/Desktop/Projects/Singularity/libs/tflite_tools$ cd tflite-tools/

(bob) leo@katana:~/Desktop/Projects/Singularity/libs/tflite_tools/tflite-tools$ ls

example_working_set.png  __init__.py  LICENSE  Pipfile  Pipfile.lock  README.md  tflite_tools  tflite_tools.py

(bob) leo@katana:~/Desktop/Projects/Singularity/libs/tflite_tools/tflite-tools$ pipenv install

Courtesy Notice: Pipenv found itself running within a virtual environment, so it will automatically use that environment, instead of creating 
its own for any project. You can set PIPENV_IGNORE_VIRTUALENVS=1 to force pipenv to ignore that environment and create its own instead. You ca
n set PIPENV_VERBOSITY=-1 to suppress this warning.
Installing dependencies from Pipfile.lock (f23fad)...
  🐍   ▉▉▉▉▉▉▉▉▉▉▉▉▉▉▉▉▉▉▉▉▉▉▉▉▉▉▉▉▉▉▉▉ 17/17 — 00:00:21
To activate this project's virtualenv, run pipenv shell.
Alternatively, run a command inside the virtualenv with pipenv run.

(bob) leo@katana:~/Desktop/Projects/Singularity/libs/tflite_tools/tflite-tools$ pipenv shell

Courtesy Notice: Pipenv found itself running within a virtual environment, so it will automatically use that environment, instead of creating its own for any project. You can set PIPENV_IGNORE_VIRTUALENVS=1 to force pipenv to ignore that environment and create its own instead. You can set PIPENV_VERBOSITY=-1 to suppress this warning.
Launching subshell in virtual environment...

(bob) leo@katana:~/Desktop/Projects/Singularity/libs/tflite_tools/tflite-tools$ python tflite_tools.py --help

usage: tflite_tools.py [-h] [-i INPUT_PATH] [-o OUTPUT_PATH]
                       [--clusters CLUSTERS] [--optimize]
                       [--csv CSV_OUTPUT_FOLDER] [--plot PLOT_FILE]
                       [--calc-macs] [--calc-size]

TFLite model analyser & memory optimizer

optional arguments:
  -h, --help            show this help message and exit
  -i INPUT_PATH         input model file (.tflite)
  -o OUTPUT_PATH        output model file (.tflite)
  --clusters CLUSTERS   cluster weights into n-many values (simulate code-book
                        quantization)
  --optimize            optimize peak working set size
  --csv CSV_OUTPUT_FOLDER
                        output model analysis in CSV format into the specified
                        folder
  --plot PLOT_FILE      plot memory usage for each operator during the
                        execution
  --calc-macs           Calculate approximate MAC usage
  --calc-size           Calculate parameter size

(bob) leo@katana:~/Desktop/Projects/Singularity/libs/tflite_tools/tflite-tools$ python tflite_tools.py -i ../../../data/ml/lite-model_spice_1.tflite

Traceback (most recent call last):
  File "tflite_tools.py", line 50, in <module>
    main()
  File "tflite_tools.py", line 24, in main
    model = TFLiteModel.load_from_file(args.input_path)
  File "/home/leo/Desktop/Projects/Singularity/libs/tflite_tools/tflite-tools/tflite_tools/tflite_model.py", line 119, in load_from_file
    return cls(bytearray(f.read()))
  File "/home/leo/Desktop/Projects/Singularity/libs/tflite_tools/tflite-tools/tflite_tools/tflite_model.py", line 114, in __init__
    self._build_graph()
  File "/home/leo/Desktop/Projects/Singularity/libs/tflite_tools/tflite-tools/tflite_tools/tflite_model.py", line 174, in _build_graph
    assert op.OutputsLength() <= 1
AssertionError

eliberis / tflite-tools

Running on official SPICE tflite model fails with assertion #6