What is a straightforward method for arranging binary digits into sets of four bits?

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A straightforward method for arranging binary digits into sets of four bits is to start from the rightmost digit and group them into sets of four going towards the left. If there are not enough digits to make a complete set of four, add leading zeros to the left. For example:

110110101010 -> 0110 1101 0101 0

10011 -> 0010 0110