Stops process unless cond is true

stop_unless(
  cond,
  message_if_false = paste("cond in not TRUE"),
  stop_if_false = TRUE,
  return_if_true = TRUE,
  return_if_false = isFALSE(return_if_true)
)

Arguments

cond: condition to test
message_if_false: message_if_false
stop_if_false: stop_if_false
return_if_true: return_if_true
return_if_false: return_if_false