| fmt | Package fmt implements formatted I/O with functions analogous to C's printf and scanf. |
| github.com/emersion/go-message | Package message implements reading and writing multipurpose messages. |
| golang.org/x/text/encoding | Package encoding defines an interface for character encodings, such as Shift JIS and Windows 1252, that can convert to and from UTF-8. |
| golang.org/x/text/encoding/charmap | Package charmap provides simple character encodings such as IBM Code Page 437 and Windows 1252. |
| golang.org/x/text/encoding/japanese | Package japanese provides Japanese encodings such as EUC-JP and Shift JIS. |
| golang.org/x/text/encoding/simplifiedchinese | Package simplifiedchinese provides Simplified Chinese encodings such as GBK. |
| golang.org/x/text/encoding/traditionalchinese | Package traditionalchinese provides Traditional Chinese encodings such as Big5. |
| io | Package io provides basic interfaces to I/O primitives. |
| mime | Package mime implements parts of the MIME spec. |
| strings | Package strings implements simple functions to manipulate UTF-8 encoded strings. |