Function from_scalar_body 

pub fn from_scalar_body(
    df: &DecisionFabric,
    n: usize,
    target: &SpatialTarget,
) -> Result<SpatialProgram, SpatialReject>

A decision fabric (an if-converted scalar body) as a Scalar stage applied element-wise over an n-element input vector: y[i] = f(x[i]).