4 files changed, 16 insertions, 0 deletions
diff --git a/exercises/13_error_handling/errors1.rs b/exercises/13_error_handling/errors1.rs
index 9767f2c..7991c42 100644
--- a/exercises/13_error_handling/errors1.rs
+++ b/exercises/13_error_handling/errors1.rs
@@ -9,6 +9,10 @@
 // Execute `rustlings hint errors1` or use the `hint` watch subcommand for a
 // hint.
 
+fn main() {
+    // You can optionally experiment here.
+}
+
 pub fn generate_nametag_text(name: String) -> Option<String> {
     if name.is_empty() {
         // Empty names aren't allowed.
diff --git a/exercises/13_error_handling/errors2.rs b/exercises/13_error_handling/errors2.rs
index 88d1bf4..051516b 100644
--- a/exercises/13_error_handling/errors2.rs
+++ b/exercises/13_error_handling/errors2.rs
@@ -29,6 +29,10 @@ pub fn total_cost(item_quantity: &str) -> Result<i32, ParseIntError> {
     Ok(qty * cost_per_item + processing_fee)
 }
 
+fn main() {
+    // You can optionally experiment here.
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
diff --git a/exercises/13_error_handling/errors4.rs b/exercises/13_error_handling/errors4.rs
index 0e5c08b..9449417 100644
--- a/exercises/13_error_handling/errors4.rs
+++ b/exercises/13_error_handling/errors4.rs
@@ -19,6 +19,10 @@ impl PositiveNonzeroInteger {
     }
 }
 
+fn main() {
+    // You can optionally experiment here.
+}
+
 #[test]
 fn test_creation() {
     assert!(PositiveNonzeroInteger::new(10).is_ok());
diff --git a/exercises/13_error_handling/errors6.rs b/exercises/13_error_handling/errors6.rs
index de73a9a..363a3b9 100644
--- a/exercises/13_error_handling/errors6.rs
+++ b/exercises/13_error_handling/errors6.rs
@@ -54,6 +54,10 @@ impl PositiveNonzeroInteger {
     }
 }
 
+fn main() {
+    // You can optionally experiment here.
+}
+
 #[cfg(test)]
 mod test {
     use super::*;