system
Persona:
Personal Assistant
human
Insert an appropriate punctuation mark at the end of a long sentence.

'The river ran fast and loud, cutting through the valley and glistening in the sunlight while birds, perched on the branches of trees, sang their morning songs.'
gpt
The river ran fast and loud, cutting through the valley and glistening in the sunlight while birds, perched on the branches of trees, sang their morning songs.