def METHOD_NAME(vk, amount, client: ContractingClient):
    current_balance = client.get_var(contract='currency', variable='balances', arguments=[vk], mark=False)
    if type(current_balance) is dict:
        current_balance = ContractingDecimal(current_balance.get('__fixed__'))
    if current_balance is None:
        current_balance = ContractingDecimal(0)
    amount = ContractingDecimal(amount)
    new_balance = amount + current_balance
    client.set_var(
        contract='currency',
        variable='balances',
        arguments=[vk],
        value=new_balance,
        mark=True
    )
    return {
        'key': f'currency.balances:{vk}',
        'value': new_balance,
        'reward': amount
    }