# Strategies FAQ

## Can I write in my own editor?

Yes. A strategy or an indicator is one `.py` file. Write it anywhere and keep it where you like. Upload a strategy on the Strategy card in Forge, or paste it into the [editor](https://oathra.dev/play) here. Tests run in Forge on oathra.app, not on your computer.

## How many strategy classes can a file hold?

One. Its class name is the default display name. See the [style guide](https://oathra.dev/docs/style-guide).

## Can a strategy trade more than one symbol?

Yes. Declare the symbols and read another one with `d["GBPUSD"]`, which has the same attributes as the main series.

## When does an order fill?

At the first real price after the bar it was decided on has closed. See [bar close and fills](https://oathra.dev/docs/concepts/bar-close-and-fills).

## Which hooks can a strategy define?

See [write a strategy](https://oathra.dev/docs/how-to/write-a-strategy) for every hook and when it runs.

## What is FORGE_API for?

It names the level of the Forge API the file was written for. A file without it, or with a level Forge does not support, is refused.

## Why does compute have to be pure?

It runs once over all the bars. It cannot read the clock, the account or a random number, so it gives the same answer every time.