# Functions
CheckAddPeer checks if the operator is to add peer on specified store.
CheckRemovePeer checks if the operator is to remove peer on specified store.
CheckTransferLeader checks if the operator is to transfer leader between the specified source and target stores.
CheckTransferLeaderFrom checks if the operator is to transfer leader out of the specified store.
CheckTransferPeer checks if the operator is to transfer peer between the specified source and target stores.
CheckTransferPeerWithLeaderTransfer checks if the operator is to transfer peer between the specified source and target stores and it meanwhile transfers the leader out of source store.
CheckTransferPeerWithLeaderTransferFrom checks if the operator is to transfer peer out of the specified store and it meanwhile transfers the leader out of the store.
WaitUntil repeatly evaluates f() for a period of time, util it returns true.
# Type aliases
CheckFunc is a condition checker that passed to WaitUntil.