the unpack function parameter [closed]

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the below function is defined in here

void unpack(const velodyne_msgs::VelodynePacket &pkt, VPointCloud &pc);

the explanation of this function is present here

if we see the method definition the it looks like we have passed two addresses as &pkt and &pc.

But if we see the explanation of definition, the first parameter looks like address and reference too.

The second parameter is looks like shared pointer. can anybody tell me what exactly it is.

I added this question cause I am getting error: no match function to call