solution.diff

diff -r unsolved/contracts/Minter.vy solved/contracts/Minter.vy
1c1
< # @version 0.3.3
---
> # @version 0.3.7
11,12c11,12
< interface Token:
<     def mint(to_addr: address, amount: uint256): nonpayable
---
> import Token as Token
> from vyper.interfaces import ERC20
14c14,15
< token: public(Token)
---
> stablecoin: public(Token)       # $crvUSD
> lending_token: public(ERC20)    # $CRV
17,18c18,20
< def __init__(token_addr: address):
<     self.token = Token(token_addr)
---
> def __init__(token_addr: address, lending_token_addr: address):
>     self.stablecoin = Token(token_addr)
>     self.lending_token = ERC20(lending_token_addr)
26c28,31
<     self.token.mint(msg.sender, quantity)
---
>     assert self.lending_token.allowance(msg.sender, self) >= quantity, "Lacks Approval"
>     assert self.lending_token.balanceOf(msg.sender) >= quantity, "Lacks Balance"
>     self.lending_token.transferFrom(msg.sender, self, quantity)
>     self.stablecoin.mint(msg.sender, quantity)
diff -r unsolved/contracts/Token.vy solved/contracts/Token.vy
1c1
< # @version ^0.2.0
---
> # @version ^0.3.7