old_contents: from reference_data.models import GeneInfo
  
  
  def get_genes_by_symbol_and_id():
      gene_symbol_to_genes = {}
      gene_id_to_genes = {}
      for gene_info in GeneInfo.objects.all().only('gene_id', 'gene_symbol').order_by('-gencode_release'):
          if gene_info.gene_symbol not in gene_symbol_to_genes:
              gene_symbol_to_genes[gene_info.gene_symbol] = gene_info
          if gene_info.gene_id not in gene_id_to_genes:
              gene_id_to_genes[gene_info.gene_id] = gene_info
      return gene_symbol_to_genes, gene_id_to_genes
  
  
  def get_genes_by_symbol():
      gene_symbol_to_genes, _ = get_genes_by_symbol_and_id()
      return gene_symbol_to_genes
  
  
  def get_genes_by_id():
      _, gene_id_to_genes = get_genes_by_symbol_and_id()
      return gene_id_to_genes
  
new_contents: from reference_data.models import GeneInfo
  
  
  def get_genes_by_symbol_and_id():
      gene_symbol_to_genes = {}
      gene_id_to_genes = {}
      for gene_info in GeneInfo.objects.all().only('gene_id', 'gene_symbol').order_by('-gencode_release'):
          if gene_info.gene_symbol not in gene_symbol_to_genes:
              gene_symbol_to_genes[gene_info.gene_symbol] = gene_info
          if gene_info.gene_id not in gene_id_to_genes:
              gene_id_to_genes[gene_info.gene_id] = gene_info
      return gene_symbol_to_genes, gene_id_to_genes
  
subject: remove unsused gene_util functions