solution = fetch("https://sagecell.sagemath.org/service", {
method: "POST",
headers: {
"Content-Type": "application/x-www-form-urlencoded"
},
body: `code=
# https://doc.sagemath.org/pdf/en/reference/power_series/power_series.pdf
R.<x> = PowerSeriesRing(QQ, default_prec=12)
res = ${input}
print(res)`
}).then((d) => d.json())