// By using the static specifier, we're indicating

// that foo() should have internal linkage.  Other

// .c files cannot see or invoke foo().

static int foo(int x) {

  return x*3 + 1;

}



// Bar is "extern" by default.  Thus, other .c files

// could declare our bar() and invoke it.

int bar(int x) {

  return 2*foo(x);

}