https://lmfit.github.io/lmfit-py/model.html
https://stackoverflow.com/questions/42658190/plotting-one-sigma-error-bars-on-a-curve-fit-line-in-scipy

http://qaru.site/questions/15434868/fitting-a-curve-over-bar-chart-python
https://docs.scipy.org/doc/scipy/reference/generated/scipy.optimize.curve_fit.html

how to build curv_fit from pandas DataFrame
https://stackoverflow.com/questions/35233664/pass-pandas-dataframe-to-scipy-optimize-curve-fit

polynomial fitting
https://sites.google.com/site/aslugsguidetopython/data-analysis/curve-fitting
syn
http://scipy-lectures.org/intro/scipy/auto_examples/plot_curve_fit.html