> For the complete documentation index, see [llms.txt](https://docs.tradesurge.co/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.tradesurge.co/platform/strategies/upload-python.md).
# Upload a Python strategy
Write your strategy as one pure Python function that turns candles into signals, then upload it.
Python strategies use the TradeSurge Strategy API. It is one small interface: candles and parameters in, signals out. If you can describe your entries and exits in terms of candles, you can write it.
## What you need
* A strategy you can express from candle data alone: open, high, low, close and volume.
* A Python file that implements `generate_signals(candles)`.
* Any settings you want to tune, declared as parameters.
## Upload it
{% stepper %}
{% step %}
### Write the function
Implement `generate_signals` so it returns signals from the candles it receives. The only signals are `enter_long`, `enter_short`, `exit_long` and `exit_short`.
{% endstep %}
{% step %}
### Declare your parameters
List each tunable setting with its type and range. Parameters can be true or false, whole numbers, decimals or short text.
{% endstep %}
{% step %}
### Upload the file
Open Strategies and upload. TradeSurge checks the code and creates a new version.
{% endstep %}
{% step %}
### Run a backtest
Open the version and start a backtest to see how it would have performed.
{% endstep %}
{% endstepper %}
{% hint style="warning" %}
The most common rejection is code that reaches outside the candles. Network calls, file access, the system clock and random numbers are all refused, because they make results impossible to repeat.
{% endhint %}
## Good to know
* Signals are evaluated when a candle closes, never mid-candle.
* Any signal outside the four allowed actions fails closed.
* Uploaded code runs in a restricted sandbox.
## Next steps
---
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