node_modules/@plotly/d3-sankey/src/sankeyLinkHorizontal.js

import {linkHorizontal} from "d3-shape";

function horizontalSource(d) {
  return [d.source.x1, d.y0];
}

function horizontalTarget(d) {
  return [d.target.x0, d.y1];
}

export default function() {
  return linkHorizontal()
      .source(horizontalSource)
      .target(horizontalTarget);
}