GenomeDescription-class
                        GenomeDescription objects
Seqinfo-class           Seqinfo objects
fetchExtendedChromInfoFromUCSC
                        Fetching chromosomes info for some of the UCSC
                        genomes
getChromInfoFromEnsembl
                        Get chromosome information for an Ensembl
                        species
getChromInfoFromNCBI    Get chromosome information for an NCBI assembly
getChromInfoFromUCSC    Get chromosome information for a UCSC genome
loadTaxonomyDb          Return a data.frame that lists the known
                        taxonomy IDs and their corresponding organisms.
mapGenomeBuilds         Mapping between UCSC and Ensembl Genome Builds
rankSeqlevels           Assign sequence IDs to sequence names
seqinfo                 Accessing/modifying sequence information
seqlevels-wrappers      Convenience wrappers to the seqlevels() getter
                        and setter
seqlevelsStyle          Conveniently rename the seqlevels of an object
                        according to a given style