Quickstart: Subscribe and Redeem USYC

import "../IERC20.sol";

interface ITeller {
  function buy(uint256 _amount) external returns (uint256);
  function sell(uint256 _amount) external returns (uint256);
}

ITeller teller = ITeller(0x5C73E1cfdD85b7f1d608F7F7736fC8C653513B7A);

// Subscribe to USYC
IERC20 usdc = IERC20(0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48);
uint256 paying = 100 * 1e6; // 100.000000 USDC
usdc.approve(address(teller), paying);
uint256 usycPurchased = teller.buy(paying);

// Redeem USYC
IERC20 usyc = IERC20(0x136471a34f6ef19fE571EFFC1CA711fdb8E49f2b);
uint256 selling = 100 * 1e6; // 100.000000 USYC
usyc.approve(address(teller), selling);
uint256 usdcPayout = teller.sell(selling);

import { Address, erc20ABI, writeContract } from "@wagmi/core";

const USYC_TELLER_ABI = [
  {
    inputs: [{ internalType: "uint256", name: "_amount", type: "uint256" }],
    name: "sell",
    outputs: [{ internalType: "uint256", name: "", type: "uint256" }],
    stateMutability: "nonpayable",
    type: "function",
  },
  {
    inputs: [{ internalType: "uint256", name: "_amount", type: "uint256" }],
    name: "buy",
    outputs: [{ internalType: "uint256", name: "", type: "uint256" }],
    stateMutability: "nonpayable",
    type: "function",
  },
] as const;

// Ethereum mainnet addresses
const USYC_TELLER_ADDRESS: Address =
  "0x5C73E1cfdD85b7f1d608F7F7736fC8C653513B7A";
const USDC_ADDRESS: Address = "0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48";
const USYC_ADDRESS: Address = "0x136471a34f6ef19fE571EFFC1CA711fdb8E49f2b";

const ONE_HUNDRED_USDC = BigInt(100_000000); // USDC uses 6 decimals
const ONE_HUNDRED_USYC = BigInt(100_000000); // USYC uses 6 decimals

// Subscribe to USYC
export const approveUSYCTellerToSpendUSDC = () =>
  writeContract({
    chainId: 1,
    address: USDC_ADDRESS,
    abi: erc20ABI,
    functionName: "approve",
    args: [USYC_TELLER_ADDRESS, ONE_HUNDRED_USDC],
  });

export const buyUSYC = () =>
  writeContract({
    address: USYC_TELLER_ADDRESS,
    chainId: 1,
    abi: USYC_TELLER_ABI,
    functionName: "buy",
    args: [ONE_HUNDRED_USDC],
  });

// Redeem USYC
export const approveUSYCTellerToSpendUSYC = () =>
  writeContract({
    chainId: 1,
    address: USYC_ADDRESS,
    abi: erc20ABI,
    functionName: "approve",
    args: [USYC_TELLER_ADDRESS, ONE_HUNDRED_USYC],
  });

export const sellUSYC = () =>
  writeContract({
    address: USYC_TELLER_ADDRESS,
    chainId: 1,
    abi: USYC_TELLER_ABI,
    functionName: "sell",
    args: [ONE_HUNDRED_USYC],
  });