improvements and fixes

rsprocess/src/set.rs

@@ -33,6 +33,7 @@ where
     fn len(&self) -> usize;
     fn is_empty(&self) -> bool;
     fn contains(&self, el: &Self::Element) -> bool;
+    fn add(&mut self, el: Self::Element);
 }
 
 pub trait ExtensionsSet {
@@ -140,6 +141,10 @@ impl BasicSet for Set {
     fn contains(&self, el: &Self::Element) -> bool {
         self.identifiers.contains(el)
     }
+
+    fn add(&mut self, el: Self::Element) {
+        self.identifiers.insert(el);
+    }
 }
 
 impl PartialEq for Set {
@@ -488,6 +493,10 @@ impl BasicSet for PositiveSet {
             false
         }
     }
+
+    fn add(&mut self, el: Self::Element) {
+        self.identifiers.insert(el.id, el.state);
+    }
 }
 
 impl PrintableWithTranslator for PositiveSet {