[Python] Run .py file that is in a subdirectory

I feel like this should be very obvious, yet I'm not finding the correct search terms. I can run a file from the root of my project, but not from a subdirectory. How do I fix this?

I have a directory tree that looks like this:

$ tree
.
├── kalman
│ ├── find_observibility.py
│ ├── __init__.py
│ ├── kalman.py
│ └── model.py


find_observibility.py imports from kalman.

If I copy find_observibility.py into the root of my project, it runs just fine. However, when I try to run it from its subdirectory, I get an error:

$ ./kalman/find_observibility.py
Traceback (most recent call last):
File "/home/tim/Documents/software/cl_kalman/./kalman/find_observibility.py", line 3, in <module>
from kalman import outputJacobian, stateJacobian, stateTransition
File "/home/tim/Documents/software/cl_kalman/kalman/kalman.py", line 6, in <module>
from kalman.model import modelOutput, stateTransition
ModuleNotFoundError: No module named 'kalman.model'; 'kalman' is not a package


Here's find_observability.py:

#! /usr/bin/env python3

from kalman import outputJacobian, stateJacobian, stateTransition
from make_flight import Rising, Rounds

if '__main__' == __name__:
print('oh my')


Here's kalman/__init__.py:

from .model import initialState, modelOutput, stateTransition
from .kalman import outputJacobian, stateJacobian


Clues would be appreciated. Solutions even more. Thanks in advance.

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