Function storage class specifiers
For a function, the storage class specifier determines the linkage
of the function. By default, function definitions have external linkage,
and can be called by functions defined in other files. 
An exception
is inline functions, which are treated by default as having internal
linkage; see Linkage of inline functions for
more information.
A storage class specifier may be used in both function declarations
and definitions. The only storage class options for functions
are:
staticextern