add find method to indexed

lib/typed/parfait/indexed.rb

@@ -133,6 +133,16 @@ module Parfait
       self
     end
 
+    def find
+      index = 1
+      while index <= self.get_length
+        item = get(index)
+        return item if yield item
+        index = index + 1
+      end
+      return nil
+    end
+
     def set_length  len
       was = self.get_length
       return if was == len

test/typed/parfait/test_list.rb

@@ -137,6 +137,15 @@ class TestList < MiniTest::Test
     end
     assert_equal 2 , counter
   end
+  def test_find
+    @list.set(1,1)
+    @list.set(2,2)
+    assert_equal 2, @list.find{|i| i == 2}
+  end
+  def test_not_find
+    @list.set(1,1)
+    assert_nil @list.find{|i| i == 3}
+  end
   def test_delete_at
     test_many_get
     assert @list.delete_at 2