Open source software like Python is designed to be developed by a collaborative effort, with sharing of libraries. No programmer will redevelop code that exists if it can be avoided, but, as everyone else has indicated, proper credit should always be given. Simply look through the forums to see people sharing everything from snippets to complex algorithms and modules. Be satisfied that you have created something others appreciate and can use, but call anyone out who does not credit your portion of the work.
Regards,
Jim