Initial data commit

Task/String-prepend/Picat/string-prepend.picat

@@ -0,0 +1,19 @@
+go =>
+
+  S = "123456789",
+  println(S),
+  S := "A" ++ S,
+  println(S),
+
+  % append
+  append("B",S,T),
+  S := T,
+  println(S),
+
+  % insert at position
+  S := insert(S,1,'C'), % note: must be a char to keep it a proper string
+  println(S),
+  % insert many characters
+  S := insert_all(S,1,"DE"),
+  println(S),
+  nl.