It should be noted that next() sends an implicit null into the generator to ensure that code execution isn't blocked if the generator is expecting a value to be sent into it and the code doesn't execute any send()
(PHP 5 >= 5.5.0, PHP 7, PHP 8)
Generator::next — Continua la ejecución del generador
Llamar a Generator::next() tiene el mismo efecto que llamar a
Generator::send() con null
como argumento.
Esta función no tiene parámetros.
No devuelve ningún valor.
It should be noted that next() sends an implicit null into the generator to ensure that code execution isn't blocked if the generator is expecting a value to be sent into it and the code doesn't execute any send()