exercise stubs - part 3 of 4 (#286)

[no important files changed]

Author: keiravillekode

exercises/practice/raindrops/source/raindrops.d

@@ -1,3 +1,8 @@
+pure string convert(immutable int n)
+{
+    // implement this function
+}
+
 unittest
 {
     immutable int allTestsEnabled = 0;

exercises/practice/reverse-string/source/reverse_string.d

@@ -1,5 +1,10 @@
 module reverse_string;
 
+pure string reverseString(immutable string value)
+{
+    // implement this function
+}
+
 unittest
 {
     immutable int allTestsEnabled = 0;

exercises/practice/rna-transcription/source/rna_transcription.d

@@ -1,5 +1,10 @@
 module rna_transcription;
 
+pure string toRna(immutable string dna)
+{
+    // implement this function
+}
+
 unittest
 {
     import std.exception : assertThrown;

exercises/practice/roman-numerals/source/roman_numerals.d

@@ -2,6 +2,11 @@ module roman_numerals;
 
 import std.stdio;
 
+string convert(ulong number)
+{
+    // implement this function
+}
+
 unittest
 {