Imports of exercise command

PathSynopsis
fmtPackage fmt implements formatted I/O with functions analogous to C's printf and scanf.
github.com/alecthomas/chroma/formatters
github.com/alecthomas/chroma/lexersPackage lexers contains the registry of all lexers.
github.com/alecthomas/chroma/styles
gopkg.in/alecthomas/kingpin.v3-unstable
io/ioutilPackage ioutil implements some I/O utility functions.
osPackage os provides a platform-independent interface to operating system functionality.