AWS Python CDK Sharing Libraries

I am using AWS CDK inside VSCODE. My project layout is such that a single directory contains multiple top-level stacks.

I would like to be able to share code between Stacks. To be specific, it is code and not cross-stack references or resources.

For instance I have a tagging function that I want to be able share and use across all stacks

   def default_tag_stacks(*args: cdk.Stack):
    for stack in args:
        cdk.Tags.of(stack).add("OU", "PlatformInfrastructure")
        cdk.Tags.of(stack).add("GovernanceLevel", "Production")
        cdk.Tags.of(stack).add("Owner", "Platform")

My editor sees the library and picks up the import, but when running

cdk synth

I get an import error. Is there path variable or another project structure I can follow so I can share code that is not part of a particular stack?

Project structure is as follows

/
 lib/tagging.py
 stack-1/app.py
 stack-2/app.py

Imports are as such

from lib.tagging import tag_all_app_stacks_default

cd stack-1
cdk synth

gives

Traceback (most recent call last):
  File "app.py", line 7, in <module>
    from lib.tagging import tag_all_app_stacks_default
ModuleNotFoundError: No module named 'lib'