# forge.indicator.warmup_expression_from_node

```python
forge.indicator.warmup_expression_from_node(node: ast.AST, settings: Mapping[str, param.Param]) -> str
```

One warm-up expression from a literal, a ``lambda self: ...`` or a ``def warmup(self)``.

The body is one expression built from whole numbers, ``self.<setting>`` of a number setting,
``+ - * //``, parentheses, ``max`` and ``min``. Anything else is
``ValueError("warmup_invalid: ...")``.

Since Forge API 1.