import { BigNumber } from "https://deno.land/x/web3@v0.11.1/types/bignumber.d.ts";
Returns a BigNumber whose value is the value of this BigNumber minus n
.
The return value is always exact and unrounded.
0.3 - 0.1 // 0.19999999999999998
x = new BigNumber(0.3)
x.minus(0.1) // '0.2'
x.minus(0.6, 20) // '0'