add tree depth calculation

...ynb_checkpoints/tania-some-other-metrics-checkpoint.ipynb

tania_scripts/.ipynb_checkpoints/transform-checkpoint.py

tania_scripts/__pycache__/transform.cpython-311.pyc

...a_scripts/supar/.ipynb_checkpoints/__init__-checkpoint.py

tania_scripts/supar/.ipynb_checkpoints/parser-checkpoint.py

tania_scripts/supar/__init__.py

tania_scripts/supar/__pycache__/__init__.cpython-310.pyc

tania_scripts/supar/__pycache__/__init__.cpython-311.pyc

tania_scripts/supar/__pycache__/__init__.cpython-39.pyc

tania_scripts/supar/__pycache__/model.cpython-310.pyc

tania_scripts/supar/__pycache__/model.cpython-311.pyc

tania_scripts/supar/__pycache__/parser.cpython-310.pyc

tania_scripts/supar/__pycache__/parser.cpython-311.pyc

...scripts/supar/__pycache__/vector_quantize.cpython-310.pyc

tania_scripts/supar/cmds/__init__.py

...a_scripts/supar/cmds/__pycache__/__init__.cpython-310.pyc

tania_scripts/supar/cmds/__pycache__/run.cpython-310.pyc

tania_scripts/supar/cmds/const/aj.py

tania_scripts/supar/cmds/const/crf.py

tania_scripts/supar/cmds/const/sl.py