| bytes | Package bytes implements functions for the manipulation of byte slices. |
| cmd/go/internal/robustio | |
| io | Package io provides basic interfaces to I/O primitives. |
| math/rand | Package rand implements pseudo-random number generators suitable for tasks such as simulation, but it should not be used for security-sensitive work. |
| os | Package os provides a platform-independent interface to operating system functionality. |
| path/filepath | Package filepath implements utility routines for manipulating filename paths in a way compatible with the target operating system-defined file paths. |
| strconv | Package strconv implements conversions to and from string representations of basic data types. |