my $rv = $self->_predecessors_complete( $self->predecessors ); ##$self->predecessors is a reference to a hash 


sub _predecessors_complete {
    my ( $self, $predecessors ) = @_;

    while ( my $p = shift  @{ $predecessors } ) {

    print "\np : $p\n";


 --this line --      if ( ! exists $self->steps->{$p} ) {
          print "\nThe job $p has not been defined in the Scheduler!\n";
          return(100);
        } else {