error fix in SelectNetworkGenes

    } else{

      # identify genes that are expressed in at least some fraction of cells

      print('before')

      print('before size')

      print(dim(expr_mat))

      gene_filter <- rowSums(expr_mat) >= round(fraction*ncol(seurat_obj));

      print('after')

      gene_list <- rownames(seurat_obj)[gene_filter]