Stake LP

• Gauge = Pool = LP contract address : 1. Getting pair address for two tokens.
• You don't necessarily have to approve LP token to the Vault contract before staking it. Vault is whitelisted by default in LP contract.

• Pending rewards will be claimed automatically, if any, when you deposit or withdraw LPs.

function deposit(address _gauge, uint256 _amount) external;
function withdraw(address _gauge, uint256 _amount) external;