pry(main)> cd Article
  pry(Article)>ls -mj --grep validate #many options here (--help to learn more), this one will list all singleton methods and search for validate methods
  #=>   _validate_callbacks

  ### at any point call 'nesting' to get an overview of where you are at.

  pry(main)> nesting

  # =>
  # Nesting status:
  # --
  # 0. main (Pry top level)
  # 1. Article