convert P&L in points to USD FinancialInstrument package

I have several currency pairs, not necessarily downloaded from online resources, it could be a regular file from disk, but for simplicity of the example and reproducibility I will download from the network.
```
library(quantmod)
getSymbols("AUD/CAD",src="oanda",from="2024-01-01")
getSymbols("CAD/CHF",src="oanda",from="2024-01-01")
getSymbols("USD/JPY",src="oanda",from="2024-01-01")
```
Now let’s calculate a simple “buy and hold” strategy in points

```
# buy and hold P&L in points
BH_AUDCAD <- AUDCAD - c(coredata(AUDCAD[1]))
BH_CADCHF <- CADCHF - c(coredata(CADCHF[1]))
BH_USDJPY <- USDJPY - c(coredata(USDJPY[1]))
```
Now I would like to calculate p&l in USD but I’m a little confused and don’t know how to do it correctly

```
library(FinancialInstrument)
currency(c("AUD", "CAD", "CHF", "USD", "JPY"))
stock(c("AUDCAD", "CADCHF", "USDJPY"), currency="USD")

PnL_USD_AUDCAD <- ....
PnL_USD_CADCHF <- ....
PnL_USD_USDJPY <- ....
```

No repository file or test is identified. Start by reviewing the FinancialInstrument currency() and stock() setup in the example, then establish the expected USD conversion for each pair and document reproducible inputs and outputs as the completion criteria.

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