docs: function appendTo(selection) {
    const targets = selection;
    const targetCount = targets.size();
    const _this = this;
    const clones = [];
  
    targets.each(function() {
      const currTarget = this;
      _this.each(function() {
        if(targetCount > 1) {
          const clone = this.cloneNode(true);
          currTarget.appendChild(clone);
          clones.push(clone);
        }
        else {
          currTarget.appendChild(this);
        }
      });
    });
  
    if (targetCount > 1) {
      this.remove();
    }
  
    return clones.length > 0 ? selectAll(clones) : this;
  }