updatePositionMargin

async def updatePositionMargin(marketId: int, margin: float):
    existing = await retrieveExistingPosition(marketId)
    if existing is None:
        print('No position to update')
        return None
    original_margin = existing.allocated_margin
    if margin > original_margin:
        amount = margin - original_margin
        print(f'Increasing margin from {original_margin} to {margin} (adding {amount})')
        await addMargin(marketId, amount)
    elif margin < original_margin:
        amount_to_extract = original_margin - margin
        print(f'Decreasing margin from {original_margin} to {margin} (extracting {amount_to_extract})')
        await extractMargin(marketId, amount_to_extract)
    else:
        print(f'Margin unchanged at {margin}')
        return MessageToDict(existing, always_print_fields_with_no_presence=True)
    existing.allocated_margin = margin
    print(f'Transaction submitted successfully (margin: {original_margin} → {margin})')
    return MessageToDict(existing, always_print_fields_with_no_presence=True)