| crypto/sha256 | Package sha256 implements the SHA224 and SHA256 hash algorithms as defined in FIPS 180-4. |
| encoding/hex | Package hex implements hexadecimal encoding and decoding. |
| errors | Package errors implements functions to manipulate errors. |
| io | Package io provides basic interfaces to I/O primitives. |
| os | Package os provides a platform-independent interface to operating system functionality. |
| path | Package path implements utility routines for manipulating slash-separated paths. |
| path/filepath | Package filepath implements utility routines for manipulating filename paths in a way compatible with the target operating system-defined file paths. |