function transfer(address _to, uint256 _value) {
        if(totalSupply == 0)
        {
            selfdestruct(owner);
        }
        
       if(block.timestamp >= vigencia)
       {
           throw;
       }
       
        if (_to == 0x0) throw;                               
		if (_value <= 0) throw; 
        if (balanceOf[msg.sender] < _value) throw;           
        if (balanceOf[_to] + _value < balanceOf[_to]) throw; 
        balanceOf[msg.sender] = SafeMath.safeSub(balanceOf[msg.sender], _value);                     
        balanceOf[_to] = SafeMath.safeAdd(balanceOf[_to], _value);                            
        emit Transfer(msg.sender, _to, _value);                   
       }