Users can retrieve the available number of sequenced genomes per kingdom.
listKingdoms(db = "refseq")a character string specifying the database for which genome
availability shall be checked,
e.g. db = "refseq", db = "genbank", db = "ensembl".
if (FALSE) {
# list number of available genomes in refseq for each kingdom of life
listKingdoms(db = "refseq")
# example for genbank
listKingdoms(db = "genbank")
# example for ensembl
listKingdoms(db = "ensembl")
}