how to change type column in laravel code example

Example 1: laravel change column

Schema::table('users', function (Blueprint $table) {
    $table->string('name', 50)->nullable()->change();
});

Example 2: laravel migration change column type

public function up()
{
    Schema::table('sometable', function (Blueprint $table) {
        $table->text('text')->change();
    });
}