Why is a Python module not being found?

The source in hypothesis_test.py, I have:

from utils import collapse_contiguous_ranges, check_number_in_range
@given(st.lists(st.integers()))
def test_collapse_contiguous_ranges(range: list[int]):
    collapsed = collapse_contiguous_ranges(range)
    for i in range:
        assert check_number_in_range(i, collapsed)
    assert collapse_contiguous_ranges(range) == [range[0], range[-1]]

Here is my command and my error:

 python -u "/Users/pitosalas/mydev/public-131-samples/memsim/memsim/tests/hypothesis_test.py"
Traceback (most recent call last):
  File "/Users/pitosalas/mydev/public-131-samples/memsim/memsim/tests/hypothesis_test.py", line 3, in <module>
    from utils import collapse_contiguous_ranges, check_number_in_range
ModuleNotFoundError: No module named 'utils'

And here is my directory structure. I've been stuck here before in other apps. I always mess around and sometimes it starts working. What can I try next?