Mainframe

It is important to state explicitly that `FyToken` expects the underlying and collateral to have a constant values of `decimals()`. It's a reasonable assumption, but there may exist tokens that have a variable value of `decimals()`.

The clone-and-own approach involves copying and adjusting open source code at one's own discretion. From the development perspective, it is initially beneficial as it reduces the amount of effort. However, from the security perspective, it involves some risks as the code may not follow the best practices, may contain a security vulnerability, or may include intentionally or unintentionally modified upstream libraries. Several files, particularly libraries, are cloned for this project.

Malicious interactions with other protocols like Uniswap may be possible. For example, the contract may be susceptible to flash loans.

Lines 60, 67: although `decimals()` usually returns the correct expected value, according to the ERC20 spec "This method can be used to improve usability, but interfaces and other contracts MUST NOT expect these values to be present" From [EIPs/eip-20.md at master · ethereum/EIPs](https://github.com/ethereum/EIPs/blob/master/EIPS/eip-20.md).

Smart contracts will often have `owner` variables to designate the person with special privileges to make modifications to the smart contract. However, this centralization of power needs to be made clear to the users, especially depending on the level of privilege the contract allows to the owner.

A block is an ordered collection of transactions from all around the network. It's possible for the ordering of these transactions to manipulate the end result of a block. A miner attacker can take advantage of this by generating and moving transactions in a way that benefits themselves. Specifically, if an account can be liquidated, only the first mined transaction(s) to deplete the total debt will succeed.

Every Solidity file specifies in the header a version number of the format `pragma solidity (^)0.4.*`. The caret (`^`) before the version number implies an unlocked pragma, meaning that the compiler will use the specified version _and above_, hence the term "unlocked".