Initial data commit

Task/Function-definition/D/function-definition.d

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+// A function:
+int multiply1(int a, int b) {
+    return a * b;
+}
+
+// Functions like "multiply1" can be evaluated at compile time if
+// they are called where a compile-time constant result is asked for:
+enum result = multiply1(2, 3); // Evaluated at compile time.
+int[multiply1(2, 4)] array;    // Evaluated at compile time.
+
+// A templated function:
+T multiply2(T)(T a, T b) {
+    return a * b;
+}
+
+// Compile-time multiplication can also be done using templates:
+enum multiply3(int a, int b) = a * b;
+
+pragma(msg, multiply3!(2, 3)); // Prints "6" during compilation.
+
+void main() {
+    import std.stdio;
+    writeln("2 * 3 = ", result);
+}