/**
 * This exercises requires the completion of a function that compares two strings and returns their concatenation
 * if the first string is greater than or equal to the second string.
 *
 * @param string1 The first string.
 * @param string2 The second string.
 * @return The concatenation of the two strings if string1 is greater than or equal to string2. Otherwise, it returns null.
 *
 * Example:
 * compareAndConcatenate("hello", "world") -> null
 * compareAndConcatenate("world", "hello") -> "worldhello"
 * compareAndConcatenate("equal", "equal") -> "equalequal"
 */
fun compareAndConcatenate(string1: String, string2: String): String? {

    return if (string1 >= string2) {
        string1 + string2
    } else {
        null
    }
}
/**
 * This exercises requires the completion of a function that compares two strings and returns their concatenation
 * if the first string is greater than or equal to the second string.
 *
 * @param string1 The first string.
 * @param string2 The second string.
 * @return The concatenation of the two strings if string1 is greater than or equal to string2. Otherwise, it returns null.
 *
 * Example:
 * compareAndConcatenate("hello", "world") -> null
 * compareAndConcatenate("world", "hello") -> "worldhello"
 * compareAndConcatenate("equal", "equal") -> "equalequal"
 */
fun compareAndConcatenate(string1: String, string2: String): String? {
/**
 * This exercises requires the completion of a function that compares two strings and returns their concatenation
 * if the first string is greater than or equal to the second string.
 *
 * @param string1 The first string.
 * @param string2 The second string.
 * @return The concatenation of the two strings if string1 is greater than or equal to string2. Otherwise, it returns null.
 *
 * Example:
 * compareAndConcatenate("hello", "world") -> null
 * compareAndConcatenate("world", "hello") -> "worldhello"
 * compareAndConcatenate("equal", "equal") -> "equalequal"
 */
fun compareAndConcatenate(string1: String, string2: String): String? {

    return if (string1 >= string2) {
        string1 + string2
    } else {
        null
    }
}