Run edited python script step by step / without reloading dataset
Read–eval–print loop (REPL)
Yes , this is what exactly you are looking for.
This is an interactive environment that takes single user inputs, executes them, and returns the result to the user; a program written in a REPL environment is executed piecewise
There are lot of Platforms which offer this.
Jupyter Notebook (Local)
Google Colab (Online)
I prefer Google colab .
Its free & we don't have to waste our Local system Resources
I work on a python script executing standard image recognition processing using tensorflow. Using Python 3.8, Tensorflow 2, Idle lauched from a virtual env.
Since I am following a tutorial, I would like to augment and execute my script chunk by chunk : e.g.

write the code for the data load
execute
write the code for training
execute only training (without reloading the data)

Is there a way to run a python script chunk by chunk, without restarting the idle shell, and keeping results from the previous steps?