download_txdb: Download transcript model from biomart
In CshlSiepelLab/DENR: Deconvolution of Expression for Nascent RNA Sequencing Data

This function creates a TxDb object from the biomaRt ensembl database, converts it to a TxDb, and returns it (WARNING: this may take a few minutes.) To view available species for a given ensembl version run view_available_txdb().

1	download_txdb(species, ensembl_version = NULL, cache = TRUE)

`species`	the species to download the TxDb for. Use the first letter of the genus and the full species as one string (e.g. homo sapiens -> hsapiens).
`ensembl_version`	The Ensembl release version. Defaults to current release.
`cache`	whether to automatically cache the downloaded TxDb (Default: TRUE)