diff --git a/src/astgen.zig b/src/astgen.zig
index 51eecb097244819dffb789f9b46d3f8ade6007ed..38464245214f696d4612a50adbc91a21258ba982 100644
--- a/src/astgen.zig
+++ b/src/astgen.zig
@@ -34,6 +34,7 @@ pub const Replacement = struct {
 
 pub const Block = struct {
     name: Type,
+    func: ?string,
     args: []const []const string,
     body: Body,
     bttm: Body,
@@ -151,6 +152,7 @@ const Parser = struct {
                 std.debug.assert(w.len > 0);
                 std.debug.assert(w[0] != '_');
                 if (std.meta.stringToEnum(Block.Type, w)) |name| {
+                    const func = if (self.tryEatSymbol("#")) self.eat(.word) else null;
                     const args = self.doArgs();
                     var children: []const Value = &.{};
                     var bottom: []const Value = &.{};
@@ -171,6 +173,7 @@ const Parser = struct {
                     self.eatSymbol("/");
                     return Value{ .block = Block{
                         .name = name,
+                        .func = func,
                         .args = args,
                         .body = children,
                         .bttm = bottom,
diff --git a/src/lib.zig b/src/lib.zig
index bd218cfd86db59dcf41d2368e555521abb8e62b2..e5048a0e8ccbba8055fbe85e815d685f38d5c437 100644
--- a/src/lib.zig
+++ b/src/lib.zig
@@ -137,6 +137,11 @@ inline fn do(alloc: std.mem.Allocator, writer: anytype, comptime value: astgen.V
                 },
                 .@"if" => {
                     comptime assertEqual(v.args.len, 1);
+                    if (v.func) |n| {
+                        const x2 = try @field(opts.Ctx, "pek_" ++ n)(alloc, x);
+                        try doif(alloc, writer, body, bottom, data, ctx, opts, x2);
+                        return;
+                    }
                     if (comptime std.meta.trait.isIndexable(T)) {
                         try doif(alloc, writer, body, bottom, data, ctx, opts, x.len > 0);
                         return;
@@ -149,6 +154,11 @@ inline fn do(alloc: std.mem.Allocator, writer: anytype, comptime value: astgen.V
                 },
                 .ifnot => {
                     comptime assertEqual(v.args.len, 1);
+                    if (v.func) |n| {
+                        const x2 = try @field(opts.Ctx, "pek_" ++ n)(alloc, x);
+                        try doif(alloc, writer, body, bottom, data, ctx, opts, !x2);
+                        return;
+                    }
                     switch (comptime TI) {
                         .Bool => try doif(alloc, writer, body, bottom, data, ctx, opts, !x),
                         .Optional => try docap(alloc, writer, body, bottom, data, ctx, opts, !x),