yieldprotocol/mentorship2022#3

1. Users can send a pre-specified ERC-20 token to a contract that also is an ERC-20, and that we will call Wrapper.
2. The Wrapper contract issues an equal number of Wrapper tokens to the sender.
3. At any point, a holder of Wrapper tokens can burn them to recover their initial deposit.

Two contracts will be required:

• ERC20 token that will be the currency
• ERC20 Wrapper that will store the currency and give Wrapper tokens to the users.

constructor()

• instantiates ERC-20 token contract to be received

deposit()

• receives ERC-20 token from usere
• checks that the token is of the pre-specified address
• mints an equivalent number of wrapper tokens to sender

redeem()

• receives wrapper ERC-20 token from user
• sends original ERC-20 to user

Ether is not an ERC-20 token. This forces all platforms to implement Ether as an edge case. Code a Wrapper that takes Ether as it's currency.