To the man on the bench at Parque Mexico who whistled my dog home

My dog slipped her lead at Parque Mexico one Tuesday morning and I spent twenty minutes running around the fountain, calling her name in a voice I did not recognise. A man on a bench stood up, whistled once, and she came straight to him. He handed me the lead and said, she is a good one, keep her close. I almost cried into the fountain. I carry a shorter lead now. I wave to him every Tuesday and he waves back. The dog does not look at me.