code: static int elevation(IBond bond, IAtom a) {
          return bond.getBegin().equals(a) ? elevation(bond) : elevation(bond) * -1;
      }
docs: Access the elevation of a bond relative to the given source atom. With a
  wedge bond if the atom <i>a</i> is the <i>point</i> end then the bond
  comes off the paper <i>above</i> the plane. If <i>a</i> is the <i>fat</i>
  end then the bond from <i>a</i> goes <i>below</i> the plane.
  
  @param bond a bond
  @param a    an atom
  @return elevation of bond