feat: Working on node builder

Sources/CliDoc/NodeBuilder.swift

@@ -28,4 +28,75 @@ public enum NodeBuilder {
     .second(component)
   }
 
+  public static func buildBlock<N: NodeRepresentable>(_ components: N...) -> _ManyNode {
+    .init(components)
+  }
+
+  // This breaks things ??
+//   public static func buildExpression<N: NodeRepresentable>(_ expression: N) -> AnyNode {
+//     expression.eraseToAnyNode()
+//   }
+
+  public static func buildOptional<N: NodeRepresentable>(_ component: N?) -> AnyNode {
+    component?.eraseToAnyNode() ?? AnyNode { Text.empty() }
+  }
+
+  public static func buildFinalResult<N: NodeRepresentable>(_ component: N) -> N {
+    component
+  }
+
+  public static func buildLimitedAvailability<N: NodeRepresentable>(_ component: N) -> N {
+    component
+  }
+
 }
+
+// These are nodes that are only used by the `NodeBuilder` / internally.
+
+// swiftlint:disable type_name
+public enum _ConditionalNode<
+  TrueNode: NodeRepresentable,
+  FalseNode: NodeRepresentable
+>: NodeRepresentable {
+  case first(TrueNode)
+  case second(FalseNode)
+
+  public func render() -> String {
+    switch self {
+    case let .first(node): return node.render()
+    case let .second(node): return node.render()
+    }
+  }
+}
+
+public struct _ManyNode: NodeRepresentable {
+  @usableFromInline
+  let nodes: [any NodeRepresentable]
+
+  @usableFromInline
+  let separator: any NodeRepresentable
+
+  @usableFromInline
+  init(
+    _ nodes: [any NodeRepresentable],
+    separator: AnyNode = Text.empty().eraseToAnyNode()
+  ) {
+    self.nodes = nodes
+    self.separator = separator
+  }
+
+  @inlinable
+  public init(_ nodes: [any NodeRepresentable], separator: any NodeRepresentable) {
+    self.nodes = nodes
+    self.separator = separator
+  }
+
+  @inlinable
+  public func render() -> String {
+    nodes.map { $0.render() }
+      .joined(separator: separator.render())
+  }
+
+}
+
+// swiftlint:enable type_name