def METHOD_NAME(evm: Evm, item_number: int) -> None:
    """
    Swap the top and the `item_number` element of the stack, where
    the top of the stack is position zero.
    If `item_number` is zero, this function does nothing (which should not be
    possible, since there is no `SWAP0` instruction).
    Parameters
    ----------
    evm :
        The current EVM frame.
    item_number :
        The stack item number (0-indexed from top of stack) to be swapped
        with the top of stack element.
    """
    # STACK
    pass
    # GAS
    charge_gas(evm, GAS_VERY_LOW)
    # OPERATION
    ensure(item_number < len(evm.stack), StackUnderflowError)
    evm.stack[-1], evm.stack[-1 - item_number] = (
        evm.stack[-1 - item_number],
        evm.stack[-1],
    )
    # PROGRAM COUNTER
    evm.pc += 1