exportPattern("^[[:alpha:]]+")
importFrom("graphics", "axis", "mtext", "title")
importFrom("stats", "chisq.test", "fisher.test", "na.omit", "pchisq",
          "qnorm", "xtabs")
importFrom("utils", "combn", "download.file", "packageVersion",
          "read.table", "write.table")
