Question: how many episodes is season 4 of the flash
[{'answer': '23', 'provenance': [{'wikipedia_id': '53527130', 'title': 'The Flash (season 4)', 'start_paragraph_id': 1, 'start_character': 181, 'end_paragraph_id': 1, 'end_character': 183, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'answer': '23 episodes', 'provenance': [{'wikipedia_id': '53527130', 'title': 'The Flash (season 4)', 'start_paragraph_id': 1, 'start_character': 181, 'end_paragraph_id': 1, 'end_character': 192, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'answer': '19', 'provenance': [{'wikipedia_id': '53527130', 'title': 'The Flash (season 4)', 'start_paragraph_id': 36, 'start_character': 391, 'end_paragraph_id': 36, 'end_character': 393, 'bleu_score': 1.0, 'section': 'Section::::Production.:Casting.\n'}]}, {'provenance': [{'wikipedia_id': '53527130', 'title': 'The Flash (season 4)', 'section': 'Section::::Abstract.', 'start_paragraph_id': 1, 'end_paragraph_id': 1, 'meta': {'evidence_span': ['The fourth season of the American television series "The Flash", which is based on the DC Comics character Barry Allen / Flash, premiered on The CW on October 10, 2017, and ran for 23 episodes until May 22, 2018.', 'The fourth season of the American television series "The Flash", which is based on the DC Comics character Barry Allen / Flash, premiered on The CW on October 10, 2017, and ran for 23 episodes', 'The fourth season of the American television series "The Flash", which is based on the DC Comics character Barry Allen / Flash, premiered on The CW on October 10, 2017, and ran for 23 episodes until May 22, 2018. The season follows a crime scene investigator with superhuman speed who fights criminals, including others who have also gained superhuman abilities. It is set in the Arrowverse, sharing continuity with the other television series of the universe, and is a spin-off of "Arrow". The season is produced by Berlanti Productions, Warner Bros. Television, and DC Entertainment, with Andrew Kreisberg and Todd Helbing serving as showrunners.']}}]}]