[Python] ImportError: cannot import name 'YOLO' from 'ultralytics' (unknown location)

I am trying to build a YOLOv8 model, and I have built it using cloning github repo of YOLOv8. https://github.com/ultralytics/ultralytics

For training the yolov8 docs say that I need to start as follows

from ultralytics import YOLO


But when I try to do the same after using pip install ultralytics, I get this error:

ImportError Traceback (most recent call last)

/tmp/ipykernel_28/546599741.py in <module>
----> 1 from ultralytics import YOLO
2
3 # Load a model
4 model = YOLO('yolov8n.yaml') # build a new model from YAML
5 model = YOLO('yolov8n.pt') # load a pretrained model (recommended for training)

ImportError: cannot import name 'YOLO' from 'ultralytics' (unknown location)

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