code: function mappingContent(mapping) {
    const { from, to, type } = mapping
    let result = {
      from: reduceBundle(from || {}),
      to: reduceBundle(to || {}),
      type: [
        type && type[0] || "http://www.w3.org/2004/02/skos/core#mappingRelation"
      ]
    }
    for (let side of ["from", "to"]) {
      if ((result[side][memberField(result[side])] || []).length == 0) {
        let scheme = mapping[side + "Scheme"]
        if (scheme && scheme.uri) {
          // Create new object to remove all unnecessary properties.
          result[side + "Scheme"] = { uri: scheme.uri }
        }
      }
    }
    return result
  }
docs: Reduce mapping to reduced fields from, to, and type.