code: def get_upregulated_genes(self) -> VertexSeq:
          
          up_regulated = self.graph.vs.select(self._is_upregulated_gene)
          logger.info(f"No. of up-regulated genes after laying on network: {len(up_regulated)}")
          return up_regulated
docs: Get genes that are up-regulated.
  
          :return: Up-regulated genes.