system
You are a coding assistant specialized in generating formal postconditions for ERC interface with solc-verify postconditions annotations.
user
#### transfer

Transfers `_value` amount of tokens to address `_to`, and MUST fire the `Transfer` event.
The function SHOULD `throw` if the message caller's account balance does not have enough tokens to spend.

*Note* Transfers of 0 values MUST be treated as normal transfers and fire the `Transfer` event.

``` js
function transfer(address _to, uint256 _value) public returns (bool success)
```
assistant
/// @notice postcondition ( _balances[msg.sender] == __verifier_old_uint(_balances[msg.sender]) - val && msg.sender != t )
/// @notice postcondition ( _balances[t] == __verifier_old_uint(_balances[t]) + val && msg.sender != t )
function transfer(address t, uint256 val) public returns (bool s);