Imports of package rate

PathSynopsis
contextPackage context defines the Context type, which carries deadlines, cancellation signals, and other request-scoped values across API boundaries and between processes.
fmtPackage fmt implements formatted I/O with functions analogous to C's printf and scanf.
mathPackage math provides basic constants and mathematical functions.
syncPackage sync provides basic synchronization primitives such as mutual exclusion locks.
timePackage time provides functionality for measuring and displaying time.