# forge.indicator.Band

```python
forge.indicator.Band(a: _OutputDecl | Level | float, b: _OutputDecl | Level | float, *, style: str = 'area', color: Color | str | None = None, color_up: Color | str | None = None, color_down: Color | str | None = None, show: Iterable[str] | None = None) -> None
```

Shade (or draw as bars) the space between two sides of one indicator.

A side is a value output of this class, a ``Level`` in its ``levels`` or a plain number.
With ``color_up`` and ``color_down`` the band takes the up colour where ``a`` is above ``b``
and the down colour where it is below; a band has no base, width or dash. It is drawing
only: a strategy reads the outputs, never a band.

Since Forge API 1.