Intuition behind k and m value

Good Afternoon
Firstly I want to say thank you for creating robust forecasting machine!
Recently I studied about Prophet
I have read Prophet documentation, and I found out that Prophet is calculate initial value of k and m
https://github.com/facebook/prophet/blob/ed0dc7a3fdca00e2f3bcd62b490093e3d123b70c/python/prophet/forecaster.py#L992-L1013
Can you help me by explain the intuition in determining initial k and m value(before optimized)
What I mean by intuition is the why/reason behind creating the formula and how the formula work
Thank you