Imports of package signal

PathSynopsis
contextPackage context defines the Context type, which carries deadlines, cancellation signals, and other request-scoped values across API boundaries and between processes.
osPackage os provides a platform-independent interface to operating system functionality.
slicesPackage slices defines various functions useful with slices of any type.
syncPackage sync provides basic synchronization primitives such as mutual exclusion locks.
syscallPackage syscall contains an interface to the low-level operating system primitives.