#import "@preview/prooftrees:0.1.0": *

#let db(x) = $bracket.l.double #x bracket.r.double$
#let isValue(x) = $#x "value"$
#let mapsto = $arrow.r.long.bar$
#let mapstostar = $op(arrow.r.long.bar)^*$
#let subst(x, v, e) = $#e [#v\/#x]$
#let TODO = text(fill: red)[*TODO*]
#let ifthenelse(e, e1, e2) = $"if" #e "then" #e1 "else" #e2$

#let conf(title, doc) = {
  show link: underline
  set page(width: 4.8in, height: 8.4in, margin: 0.3in)

  [
    = #text(size: 24pt)[#title]
    #doc
  ]
}