CNN  —  Celine Dion made a surprise video appearance at Eurovision on Tuesday, 37 years after winning the song contest for this year’s host nation, Switzerland. The Canadian-born star delivered a heartfelt message to contestants, organizers and viewers at the semi-final event. The singer won the contest for Switzerland in 1988 with “Ne partez pas sans moi.” She competed against singers from 20 other countries in Dublin, Ireland. Eurovision rules do not require contestants to be citizens of the