Function: withdraw()

This allows withdrawing from the contract.

Branches and code coverage

Intended branches

• Ensure that a user can afford the withdrawal. Ensured through withdrawAmount[msg.sender].

  Test coverage

• Update the withdrawAmount mapping for the user.

  Test coverage

• If the user has nothing to withdraw, return early.

  Test coverage

• If want == weth, withdraw WETH and transfer ETH to the user.

  Test coverage

• If want != weth, transfer want tokens to the user.

  Test coverage

Negative behavior

• Should not allow transferring more than the user can afford.

  Negative test