How to call "velodyne_rawdata::RawData::unpack()" method

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Hi, I am currently iterating over velodyne bag and can get VelodynePackets from VelodyneScan messages. Now I want to call unpack() method using this VelodynePackets. What I have done is when I got Velodyne packet I create one pointer and point it to VelodynePacket, which is my first parameter to unpack() method as.

velodyne_msgs::VelodynePacket veloPack;
const velodyne_msgs::VelodynePacket *veloPackPtr = &veloPack;

For Second parameter I have Created the instance of VPointCloud and create one pointer to point it as:

VPointCloud pointCld;
VPointCloud *pointCldPtr = &pointCld;;

Now I call unpack method as,

velodyne_rawdata::RawData::unpack(veloPackPtr, pointCldPtr);

but it shows error: No matching method for unpack() as

error: no matching function for call to ‘velodyne_rawdata::RawData::unpack(const VelodynePacket*&, VPointCloud*&)’

Any help would be appreciated. thank you in advance :)