let surround = (value, prefix, suffix) => prefix ++ value ++ suffix;
let has_prefix = (value, prefix) => String.starts_with(value, prefix);

test "surround composes delimiters" {
  expect surround("ship", "[", "]") == "[ship]";
}

test "has_prefix checks the beginning only" {
  expect has_prefix("shipping", "ship");
  expect has_prefix("shipping", "ping") == False;
}