  Pythonic code is idiomatic code that follows guiding principles and practices
within the Python community. Offering performance and readability benefits,
Pythonic code is claimed to be widely adopted by experienced Python developers,
but can be a learning curve to novice programmers. To aid with Pythonic
learning, we create an automated tool, called Teddy, that can help checking the
Pythonic idiom usage. The tool offers a prevention mode with Just-In-Time
analysis to recommend the use of Pythonic idiom during code review and a
detection mode with historical analysis to run a thorough scan of idiomatic and
non-idiomatic code. In this paper, we first describe our tool and an evaluation
of its performance. Furthermore, we present a case study that demonstrates how
to use Teddy in a real-life scenario on an Open Source project. An evaluation
shows that Teddy has high precision for detecting Pythonic idiom and
non-Pythonic code. Using interactive visualizations, we demonstrate how novice
programmers can navigate and identify Pythonic idiom and non-Pythonic code in
their projects. Our video demo with the full interactive visualizations is
available at https://youtu.be/vOCQReSvBxA.
