Remove unused helper functions.

hosts

@@ -344,54 +344,6 @@ _join() {
   printf "%s" "${@/#/${_delimiter}}" | tr -d '[:space:]'
 }
 
-# _blank()
-#
-# Usage:
-#   _blank "$an_argument"
-#
-# Exit Status:
-#   0  If the argument is not present or null.
-#   1  If the argument is present and not null.
-_blank() {
-  [[ -z "${1:-}" ]]
-}
-
-# _present()
-#
-# Usage:
-#   _present "$an_argument"
-#
-# Exit Status:
-#   0  If the argument is present and not null.
-#   1  If the argument is not present or null.
-_present() {
-  [[ -n "${1:-}" ]]
-}
-
-# _interactive_input()
-#
-# Usage:
-#   _interactive_input
-#
-# Exit Status:
-#   0  If the current input is interactive (eg, a shell).
-#   1  If the current input is stdin / piped input.
-_interactive_input() {
-  [[ -t 0 ]]
-}
-
-# _piped_input()
-#
-# Usage:
-#   _piped_input
-#
-# Exit Status:
-#   0  If the current input is stdin / piped input.
-#   1  If the current input is interactive (eg, a shell).
-_piped_input() {
-  ! _interactive_input
-}
-
 # _print_entries()
 #
 # Usage: