* string `cute #puppies` is encoded as `cute%20%23puppies` when used as a query parameter value.
 *
 * ### Percent encoding
 *
 * Percent encoding replaces a character (like `\ud83c\udf69`) with its UTF-8 hex bytes (like
 * `%F0%9F%8D%A9`). This approach works for whitespace characters, control characters, non-ASCII
 * characters, and characters that already have another meaning in a particular context.
 *