Cannot find a module imported by another module

I have a file structure like this

└── myproject
    ├── src
        ├── a.py
        ├── b.py

module a contains a class that is imported in by module b like this:

from src.a import some_class

when I try to import b from another class:

from myproject.src import b

I get this error:

from src.a import some_class

ModuleNotFoundError: No module named 'src'

why can’t python find package src? how can I solve this?