| encoding/json | Package json implements encoding and decoding of JSON as defined in RFC 7159. |
| github.com/coreos/etcd/raft | Package raft sends and receives messages in the Protocol Buffer format defined in the raftpb package. |
| log | Package log implements a simple logging package. |
| math | Package math provides basic constants and mathematical functions. |
| sync | Package sync provides basic synchronization primitives such as mutual exclusion locks. |
| time | Package time provides functionality for measuring and displaying time. |