code: def databasesKEGG(organism,ens_ids):
      all_genes=urlopen("http://rest.kegg.jp/list/"+organism).read()
      all_genes=all_genes.split("\n")
      dbs=[]
      while len(dbs) == 0:
          for g in all_genes:
              if len(dbs) == 0:
                  kid = g.split("\t")[0]
                  gene=urlopen("http://rest.kegg.jp/get/"+kid).read()
                  DBLINKS=gene.split("\n")
                  DBLINKS=[ s for s in DBLINKS if ":" in s ]
                  for d in DBLINKS:
                      test=d.split(" ")
                      test=test[len(test)-1]
                      if test in ens_ids:
                          DBLINK=[ s for s in DBLINKS if test in s ]
                          DBLINK=DBLINK[0].split(":")
                          DBLINK=DBLINK[len(DBLINK)-2]
                          dbs.append(DBLINK)
              else:
                  break
      ens_db=dbs[0].split(" ")
      ens_db=ens_db[len(ens_db)-1]
      test_db=urlopen("http://rest.genome.jp/link/"+ens_db+"/"+organism).read()
      test_db=test_db.split("\n")
      if len(test_db) == 1:
          print("For "+organism+" the following db was found: "+ens_db)
          print("This database does not seem to be valid KEGG-linked database identifier")
          print("For \n'hsa' use 'ensembl-hsa'\n'mmu' use 'ensembl-mmu'\n'cel' use 'EnsemblGenomes-Gn'\n'dme' use 'FlyBase'")
          sys.stdout.flush()
          ens_db = None
      else:
          print("For "+organism+" the following db was found: "+ens_db)
          sys.stdout.flush()
      return ens_db