Function canonical_of_differences 

pub fn canonical_of_differences(
    graph: &DiffGraph,
    file: &str,
    position: Position,
) -> Result<Polynomial, Error>

Expands a DiffGraph into its canonical polynomial over the input coordinates: a leaf is the minuend coordinate minus the subtrahend coordinate and a negation is 0 - x.

For the graph a difference form was made from, the result equals canonical of that graph.

Errors

Returns the error of canonical, at position in file, when the expansion is too large.