`run`: Refactor for controllability

[tony]

subprocess executes immediately. it should be possible to pass this around and defer to run() or execute()

• subprocess
• to the extent possible, annotate and pass through to the standard library
• the instantiated wrapper class should

  • allow introspection

  • mutability

  • terraria dreamworld:

    • potentially an option to freeze
      • tamper-proof object (is such a thing possible?)
• ...