change=z.deriveCol(r=>r.Inflow-r.Outflow,df_summed)//using deriveCol to make a new array
// Your code here
df_inoutFlow=z.addCol("inflow-outflow",change,df_summed)//adding that array to df_summed to make a new array
// Your code here
// Your code here
d3=require("d3")
Purpose-built for displays of data
Observable is your go-to platform for exploring data and creating expressive data visualizations. Use reactive JavaScript notebooks for prototyping and a collaborative canvas for visual data exploration and dashboard creation.