Member "slice" not found or not visible after argument-dependent lookup in struct Ballot.Proposal storage ref[ ] storage ref

I'm new to solidity, I'm writing a smart contract for ballot process but getting the error in my ballot function in the line proposals = proposals.slice(0, _numProposals);. I've traversed all the relevant questions to it but finally concluded to ask you people when my problem seemed different from others.

pragma solidity ^0.8.10; contract Ballot { struct Voter { uint weight; bool voted; uint8 vote; } struct Proposal { uint voteCount; } enum Stage {Init, Reg, Vote, Count} Stage public stage = Stage.Init; address chairperson; mapping(address => Voter) voters; Proposal[] proposals; uint startTime; /// Create a new ballot with $(_numProposals) different proposals. function ballot(uint8 _numProposals) public { chairperson = msg.sender; voters[chairperson].weight = 2; proposals = proposals.slice(0, _numProposals); stage = Stage.Reg; startTime = block.timestamp; } 

I'm getting the same error after I've also added proposals = proposals.slice[0 : _numProposals];. Please explain to me in detail what is the root cause?

Thanks in advance.