[Python] Consolidating data with multiple columns in Pandas [duplicate]

I have an excel file, with 4 columns, namely "Item", "Size", "Price", "Quantity".

I would like to combine all the items with same value in "Item", "Size", "Price", and sum up their "Quantity" into a single entry, and keep the sorting order.

For example:

Item. Size. Price Quantity
A 2-3cm 0.5 10
A 1-2cm 0.6 20
B 2cm 0.7 30
A 1-2cm 0.6 40

Desired Output:

Item. Size. Price Quantity
A 2-3cm 0.5 10
A 1-2cm 0.6 60
B 2cm 0.7 30

I tried to use groupby method, but the results seem not correct. Any idea to solve this in excel365 + Python Pandas?

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