read.fasta(file = system.file("sequences/ct.fasta.gz", package = "seqinr"), 
  seqtype = c("DNA", "AA"), as.string = FALSE, forceDNAtolower = TRUE,
  set.attributes = TRUE, legacy.mode = TRUE, seqonly = FALSE, strip.desc = FALSE,
  whole.header = FALSE,
  bfa = FALSE, sizeof.longlong = .Machine$sizeof.longlong,
  endian = .Platform$endian, apply.mask = TRUE)