oups
  let allGroups = data.nodes.map(d => d.grp)
  allGroups = [...new Set(allGroups)]

  // A color scale for groups:
  const color = d3.scaleOrdinal()
    .domain(allGroups)
    .range(d3.schemeSet3);

  // A linear scale for node size
  const size = d3.scaleLinear()
    .domain([1,10])
    .range([0.5,8]);

  // A linear scale to position the nodes on the X axis
  const x = d3.scalePoint()
    .range([0, width])
    .domain(allNodes)

  // In my input data, links are provided between nodes -id-, NOT bet