function toString() { // eslint-disable-line stdlib/no-redeclare
	/* eslint-disable no-invalid-this */
	var str = '' + this.re;
	if ( this.im < 0 ) {
		str += ' - ' + (-this.im);
	} else {
		str += ' + ' + this.im;
	}
	str += 'i';
	return str;
}
Serializes a complex number as a string.

@private
@returns {string} serialized complex number