From 78beeebe8f2aca6e11f5e0ff6bbb2faaa8c50d39 Mon Sep 17 00:00:00 2001
From: Tyler Goodlet <jgbt@protonmail.com>
Date: Thu, 12 Jun 2025 23:22:46 -0400
Subject: [PATCH] Augment `nest_from_op()` with a `nest_prefix: str`

Such that the caller can pass chars they'd like to prefix the first line
of the (indented) `tree_str`, commonly we use '|_' for "obj fields".
---
 tractor/devx/pformat.py | 27 ++++++++++++++++++---------
 1 file changed, 18 insertions(+), 9 deletions(-)

diff --git a/tractor/devx/pformat.py b/tractor/devx/pformat.py
index b9e1ca48..f2973441 100644
--- a/tractor/devx/pformat.py
+++ b/tractor/devx/pformat.py
@@ -328,6 +328,8 @@ def nest_from_op(
     # NOTE: so move back-from-the-left of the `input_op` by
     # this amount.
     back_from_op: int = 0,
+    nest_prefix: str = ''
+
 ) -> str:
     '''
     Depth-increment the input (presumably hierarchy/supervision)
@@ -336,15 +338,22 @@ def nest_from_op(
     `tree_str` to nest content aligned with the ops last char.
 
     '''
+    indented_tree_str: str = textwrap.indent(
+        tree_str,
+        prefix=' ' *(
+            len(input_op)
+            -
+            (back_from_op + 1)
+        ),
+    )
+    # inject any provided nesting-prefix chars
+    # into the head of the first line.
+    if nest_prefix:
+        indented_tree_str: str = (
+            f'{nest_prefix}'
+            f'{indented_tree_str[len(nest_prefix):]}'
+        )
     return (
         f'{input_op}\n'
-        +
-        textwrap.indent(
-            tree_str,
-            prefix=(
-                len(input_op)
-                -
-                (back_from_op + 1)
-            ) * ' ',
-        )
+        f'{indented_tree_str}'
     )