code: function simpleNormalizeChildren (children) {
    for (var i = 0; i < children.length; i++) {
      if (Array.isArray(children[i])) {
        return Array.prototype.concat.apply([], children)
      }
    }
    return children
  }
docs: 1. When the children contains components - because a functional component may return an Array instead of a single root. In this case, just a simple normalization is needed - if any child is an Array, we flatten the whole thing with Array.prototype.concat. It is guaranteed to be only 1-level deep because functional components already normalize their own children.