CFU_leapyear<-function( year ) {
#
#
#
#
leap=FALSE
if ( year %% 4 == 0 ) {
  leap=TRUE
  if ( year %% 100 == 0 ) {
    leap=FALSE
    if ( year %% 400 == 0 ) {
      leap=TRUE
    }
  } 
}
#
# Output
#
leap
}
