Suggestions for lua-placeholders

The following packages have something in common with the package lua-placeholders. The packages are ordered in decreasing similarity.

Package lua-calendrica: Lua implementation of Calendrical Calculations by Dershowitz & Reingold
Package lua-visual-debug: Visual debugging with LuaLaTeX
Package addtoluatexpath: Add paths to Lua packages and input TeX files
Package chinese-jfm: Luatexja-jfm files for Chinese typesetting
Package luakeyval: A minimal key/value system for LuaTeX based on token.scan_key_cs
Package luakeys: A Lua module for parsing key-value options
Package fits-astro: Retrieving FITS file header information in LuaTeX
Package lparse: Parse macro arguments with Lua using xparse-like specification
Package lualibs: Additional Lua functions for LuaTeX macro programmers
Package lua-tinyyaml: A tiny YAML (subset) parser in pure Lua
Package tsvtemplate: Apply a template to a tsv file
Package luapackageloader: Allow LuaTeX to load external Lua packages
Package luatexja: Typeset Japanese with Lua(La)TeX
Package nodetree: Visualize node lists in a tree view
Package luatex-type-definitions: Type definitions for the Lua API of LuaTeX
Package collargs: Collect arguments of any command
Package localloc: Macros for localizing TeX register allocations
Package tokmap: Iterate over a token list expandably, without dropping spaces or braced groups
Package plainpkg: A minimal method for making generic packages
Package lua-uni-algos: Unicode algorithms for LuaTeX
Package lua-widow-control: Automatically remove widows and orphans from any document
Package unibidi-lua: Unicode bidi algorithm implementation for various LuaTeX formats
Package etoolbox-generic: A loader for etoolbox.sty in non-LaTeX formats
Package calcfrac: Calculates the value of an expression containing fractions
Package fltpoint: Simple floating point arithmetic
Package langcode: Simple language-dependent settings based on language codes
Package advice: Extend commands and environments
Package opbible: Creating a study Bible with OpTeX
Package expkv-cs: Define expandable key=val macros using expkv
Package ltxcmds: Some LaTeX kernel commands for general use
Package namedef: TeX definitions with named parameters