Function refresh_external_measure 

pub fn refresh_external_measure(
    model: &mut Model,
    timeout: Duration,
    measure: MeasureId,
) -> Result<usize, ExternalError>

Recompute an external-function measure’s cells by invoking its function over its argument measures, coordinate by coordinate. Returns the number of cells written. If the function fails at any coordinate (an exception, a timeout, no usable sandbox), this returns ExternalError::Eval and leaves the measure’s previous cells untouched: the results are input cells, and an error value cannot be stored as one.

The measure is populated over the set of coordinates for which every argument measure has a value (the natural join of the arguments’ cells).