| encoding/hex | Package hex implements hexadecimal encoding and decoding. |
| fmt | Package fmt implements formatted I/O with functions analogous to C's printf and scanf. |
| go.opencensus.io/trace | Package trace contains support for OpenCensus distributed tracing. |
| go.opencensus.io/trace/propagation | Package propagation implements the binary trace context format. |
| go.opencensus.io/trace/tracestate | Package tracestate implements support for the Tracestate header of the W3C TraceContext propagation format. |
| net/http | Package http provides HTTP client and server implementations. |
| net/textproto | Package textproto implements generic support for text-based request/response protocols in the style of HTTP, NNTP, and SMTP. |
| regexp | Package regexp implements regular expression search. |
| strings | Package strings implements simple functions to manipulate UTF-8 encoded strings. |