(e=vm'2) evm2 is an evm that runs inside the evm native to Go-Ethereum.
What is EVM2?
Made for Go Ethereum, and deployable on any OS as an isolated client, evm2 runs within Geth to allow tests and debugging to happen without external constraints affecting expected outcomes. Developers can use tracing analysis methods to go beyond transaction-level understanding to smart contract execution, into the detailed events around calls and transitions by the smart contracts themselves.