message: Add a 'clear' method to map.
diff: @@ -37,6 +37,11 @@ where
  }
  }
  + /// Clears the map. Keeps the allocated memory for future use.
  + pub fn clear(&mut self) {
  + self.elems.clear();
  + }
  +
  /// Returns the size of this map.
  pub fn len(&self) -> usize {
  self.elems.len()
  