Clean codebase

[fdebrain]

Describe the solution you'd like Simplify and clean the current code. A few suggestions would be:

• Use decorators to handle the call of vega_lite_chart and arguments that do not change (data)
• Reduce duplicated code by combining existing similar functions into one (should not add complexity).
• Reduce complexity by splitting big functions into simple ones.
• Make sure variable/function naming is consistent.
• Add docstrings to functions.
• Feel free to add your suggestions in this issue