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

* Moves _value tokens to target.
* Must revert if the sender’s balance is lower than the specified amount.

Observations:
* Transfers of 0 tokens should trigger the `Transfer` event as usual.

``` js
function transfer(address ____target, 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);