 
   equals: (other) -> seq.equals @, other
 
-# Here's a quick shortcut for the Triangle constructor.
-tri = (a, b, c) -> new Triangle a, b, c
-
 
 # ----
 

      else if seq.find([[a, b], [b, c], [c, a]], ([p, q]) => @third p, q)
        throw new Error "Orientation mismatch."
      else
        t = tri a, b, c
        added = [[[a, b], [t, c]], [[b, c], [t, a]], [[c, a], [t, b]]]
        new Triangulation @third__.plusAll added


      trace -> "flip [#{T.triangulation__.toSeq().join ', '}], #{a}, #{b}"
      c = T.third a, b
      d = T.third b, a
      S = T.triangulation__.minus(a,b,c).minus(b,a,d).plus(b,c,d).plus(a,d,c)
      children = seq [S.triangle(c, d), S.triangle(d, c)]
      new T.constructor(
        S, T.sites__,
        T.children__.plus([T.triangle(a,b), children],
                          [T.triangle(b,a), children])
      )

    # The private function `doFlips` takes a triangulation and a stack of
