use dark theme with jupyter notebook code example

Example 1: jupyter notebook dark theme

1. pip install jupyterthemes
2. jt -t chesterish -fs 16 -nfs 14 -tfs 14 -ofs 16 -dfs 14 -cellw 1600 -T -N -kl -f anka -nf anka -tf anka

Example 2: jupyter notebook plot background dark theme

copiedimport matplotlib.pyplot as plt  
plt.style.use('dark_background')