| flag | Package flag implements command-line flag parsing. |
| fmt | Package fmt implements formatted I/O with functions analogous to C's printf and scanf. |
| golang.org/x/tools/benchmark/parse | Package parse provides support for parsing benchmark results as generated by 'go test -bench'. |
| math | Package math provides basic constants and mathematical functions. |
| os | Package os provides a platform-independent interface to operating system functionality. |
| sort | Package sort provides primitives for sorting slices and user-defined collections. |
| strconv | Package strconv implements conversions to and from string representations of basic data types. |
| text/tabwriter | Package tabwriter implements a write filter (tabwriter.Writer) that translates tabbed columns in input into properly aligned text. |