Hindiको ‎(ko)Accusative Preposition.

It marks the object of an action. मैंने उसको बुलाया था - Maine Us**ko** Bulaaya Tha (I had for called **him**) एक दिन लुई को डिप्लोमा दिया गया था - Ek din, Louis **ko** diploma diya gyaa tha (One day, **Louis** was given a diploma) I'd imagine most languages would have a preposition or grammatical case for something like this.