wip: Can't seem to get the node modifiers working properly.

Sources/CliDoc2/Nodes.swift

@@ -0,0 +1,105 @@
+public struct AnyTextNode: TextNode {
+  @usableFromInline
+  var makeContent: () -> String
+
+  @inlinable
+  public init<T: TextNode>(_ node: T) {
+    self.makeContent = node.render
+  }
+
+  @inlinable
+  public func render() -> String {
+    makeContent()
+  }
+}
+
+public extension TextNode {
+  func eraseToAnyTextNode() -> AnyTextNode {
+    .init(self)
+  }
+}
+
+public struct Group: TextNode {
+  @usableFromInline
+  var content: [any TextNode]
+
+  @usableFromInline
+  var separator: any TextNode
+
+  @usableFromInline
+  init(
+    content: [any TextNode],
+    separator: any TextNode = "\n"
+  ) {
+    self.content = content
+    self.separator = separator
+  }
+
+  @inlinable
+  public init(
+    separator: any TextNode = "\n",
+    @TextBuilder content: () -> any TextNode
+  ) {
+    let content = content()
+    if let many = content as? NodeContainer {
+      self.content = many.nodes
+    } else {
+      self.content = [content]
+    }
+    self.separator = separator
+  }
+
+  @inlinable
+  public func render() -> String {
+    content.reduce("") {
+      $0 + $1.render() + separator.render()
+    }
+  }
+}
+
+public struct Label: TextNode {
+  @usableFromInline
+  var node: any TextNode
+
+  @inlinable
+  public init(@TextBuilder _ content: () -> any TextNode) {
+    self.node = content()
+  }
+
+  @inlinable
+  public init(_ node: any TextNode) {
+    self.node = node
+  }
+
+  @inlinable
+  public func render() -> String {
+    node.render()
+  }
+}
+
+public struct Note: TextNode {
+  @usableFromInline
+  var label: any TextNode
+
+  @usableFromInline
+  var content: any TextNode
+
+  @usableFromInline
+  var separator: any TextNode = " "
+
+  @inlinable
+  public init(
+    separator: any TextNode = " ",
+    @TextBuilder _ label: () -> any TextNode,
+    @TextBuilder content: () -> any TextNode
+  ) {
+    self.separator = separator
+    self.label = label()
+    self.content = content()
+  }
+
+  @inlinable
+  public func render() -> String {
+    Group(content: [label, content], separator: separator).render()
+  }
+}