diff --git a/README.md b/README.md
index 14f1fef..28d5de0 100644
--- a/README.md
+++ b/README.md
@@ -118,8 +118,8 @@ var result:Stream = s.filter(function(item:Item):Boolean{
 });
 
 // 2. using provided global functions(can compare Boolean, Number, Date, XML, String types)
-//    supports nested properties i.e. prop("prop.prop.prop")
-var result:Stream = s.filter(gt(prop("price"), 1));
+//    supports nested properties i.e. member("prop.prop.prop")
+var result:Stream = s.filter(gt(member("price"), 1));
 
 // 3. using Proxy magick and global functions
 var result:Stream = s.price(gt(_, 1)); 
diff --git a/source/com/kemsky/$.as b/source/com/kemsky/$.as
index dee2423..3aeb36b 100644
--- a/source/com/kemsky/$.as
+++ b/source/com/kemsky/$.as
@@ -48,6 +48,11 @@ package com.kemsky
                 //$ from list
                 return new Stream(arg.toArray());
             }
+            else if(arg == null || arg === undefined)
+            {
+                //ignore empty arg
+                return new Stream();
+            }
             else
             {
                 //$ from one item
diff --git a/source/com/kemsky/Stream.as b/source/com/kemsky/Stream.as
index b43e7b9..f48b102 100644
--- a/source/com/kemsky/Stream.as
+++ b/source/com/kemsky/Stream.as
@@ -300,10 +300,10 @@ package com.kemsky
          * @example
          * <pre>
          *     var s1:Stream = $(1, 2, 3);
-         *     var s2:Stream = $(1, 2, 3);
+         *     var s2:Stream = $("1", "2", "3");
          *     var z:Stream = s1.zip(s2);
          *     trace(z);
-         *     //Stream{Stream{1, 1}, Stream{2, 2}, Stream{3, 3}}
+         *     //Stream{Stream{1, "1"}, Stream{2, "2"}, Stream{3, "3"}}
          * </pre>
          * @return A new list of lists created from the items and their corresponding items from another strea.
          * @internal immutable
@@ -1236,7 +1236,7 @@ package com.kemsky
          *     var item2:Object = {id: 2, key: "key1"};
          *     var item3:Object = {id: 3, key: "key2"};
          *     var s:Stream = $(item1, item2, item3);
-         *     var d:Dictionary = s.dictionary(prop("key"));
+         *     var d:Dictionary = s.dictionary(member("key"));
          *     trace(d["key1"]);
          *     //Stream{item1, item2}
          *     trace(d["key2"]);
@@ -1313,7 +1313,7 @@ package com.kemsky
          *     var item2:Object = {id: 2, key: "key1"};
          *     var item3:Object = {id: 3, key: "key2"};
          *     var s:Stream = $(item1, item2, item3);
-         *     var d:Object = s.object(prop("key"));
+         *     var d:Object = s.object(member("key"));
          *     trace(d["key1"]);
          *     //Stream{item1, item2}
          *     trace(d["key2"]);
diff --git a/source/com/kemsky/combine.as b/source/com/kemsky/combine.as
index 2fc4f54..50028aa 100644
--- a/source/com/kemsky/combine.as
+++ b/source/com/kemsky/combine.as
@@ -1,7 +1,6 @@
 package com.kemsky
 {
     /**
-     * @private
      * Creates combined function
      * @param rest a list of functions
      * @return combined function
diff --git a/source/com/kemsky/filters/prop.as b/source/com/kemsky/filters/member.as
similarity index 90%
rename from source/com/kemsky/filters/prop.as
rename to source/com/kemsky/filters/member.as
index 0d78df3..3ee6009 100644
--- a/source/com/kemsky/filters/prop.as
+++ b/source/com/kemsky/filters/member.as
@@ -2,10 +2,10 @@ package com.kemsky.filters
 {
     /**
      * Creates function that extracts named property from value
-     * @param name name of the property (nested properties are supported: 'prop.prop1.prop2')
-     * @return function function that extracts named property from value
+     * @param name name of the property or method (nested properties are supported: 'prop.prop1.prop2')
+     * @return function function that extracts named property or method from value
      */
-    public function prop(name:String):Function
+    public function member(name:String):Function
     {
         var path:Array = name.split(".");
 
diff --git a/testSrc/com/kemsky/TestStream.as b/testSrc/com/kemsky/TestStream.as
index 641895a..5f614f7 100644
--- a/testSrc/com/kemsky/TestStream.as
+++ b/testSrc/com/kemsky/TestStream.as
@@ -3,7 +3,7 @@ package com.kemsky
     import com.kemsky.filters._;
     import com.kemsky.filters.eq;
     import com.kemsky.filters.gt;
-    import com.kemsky.filters.prop;
+    import com.kemsky.filters.member;
     import com.kemsky.support.stream_internal;
 
     import flash.utils.ByteArray;
@@ -23,6 +23,16 @@ package com.kemsky
         }
 
 
+        [Test]
+        public function testFactory():void
+        {
+            var s:Stream = $(null);
+            assertEquals(s.length, 0);
+
+            var s1:Stream = $(null, undefined);
+            assertEquals(s1.length, 2);
+        }
+
         [Test]
         public function testVector():void
         {
@@ -153,8 +163,8 @@ package com.kemsky
             var item1:Item = new Item("item1", 1);
             var item2:Item = new Item("item2", 2);
 
-            assertEquals($(item1, item2).max(prop("price")), item2);
-            assertEquals($().max(prop("price"), 1), 1);
+            assertEquals($(item1, item2).max(member("price")), item2);
+            assertEquals($().max(member("price"), 1), 1);
 
             try
             {
@@ -176,8 +186,8 @@ package com.kemsky
             var item1:Item = new Item("item1", 1);
             var item2:Item = new Item("item2", 2);
 
-            assertEquals($(item1, item2).min(prop("price")), item1);
-            assertEquals($().min(prop("price"), 1), 1);
+            assertEquals($(item1, item2).min(member("price")), item1);
+            assertEquals($().min(member("price"), 1), 1);
 
             try
             {
@@ -316,7 +326,7 @@ package com.kemsky
         {
             var item:Item = new Item("name1", 5, 0);
             var s:Stream = $(item);
-            assertEquals(s.map(prop("name")).first, "name1");
+            assertEquals(s.map(member("name")).first, "name1");
         }
 
         [Test]
@@ -504,7 +514,7 @@ package com.kemsky
 
             var s:Stream = $(item1, item2);
 
-            var d:Dictionary = s.dictionary(prop("name"));
+            var d:Dictionary = s.dictionary(member("name"));
             assertEquals(d["1"], item1);
             assertEquals(d["2"], item2);
 
@@ -521,7 +531,7 @@ package com.kemsky
 
             var s:Stream = $(item1, item2);
 
-            var d:Object = s.object(prop("name"), prop("price"));
+            var d:Object = s.object(member("name"), member("price"));
             assertEquals(d["1"], item1.price);
             assertEquals(d["2"], item2.price);
         }
diff --git a/testSrc/com/kemsky/filters/TestFilters.as b/testSrc/com/kemsky/filters/TestFilters.as
index dd2fd21..99d1887 100644
--- a/testSrc/com/kemsky/filters/TestFilters.as
+++ b/testSrc/com/kemsky/filters/TestFilters.as
@@ -92,8 +92,8 @@ package com.kemsky.filters
 
             var s:Stream = $(item1, item2);
 
-            assertEquals(s.filter(eq(prop("bool"), true)).first, item2);
-            assertEquals(s.filter(eq(prop("bool"), false)).first, item1);
+            assertEquals(s.filter(eq(member("bool"), true)).first, item2);
+            assertEquals(s.filter(eq(member("bool"), false)).first, item1);
         }
 
         [Test]
@@ -183,7 +183,7 @@ package com.kemsky.filters
 
             var s:Stream = $(item1, item2);
 
-            var result:Stream = s.filter(gt(prop("price"), 1));
+            var result:Stream = s.filter(gt(member("price"), 1));
             assertEquals(result.length, 1);
             assertEquals(result.first, item2);
 
@@ -195,19 +195,19 @@ package com.kemsky.filters
             assertEquals(result.length, 1);
             assertEquals(result.first, item2.price);
 
-            result = s.filter(ge(prop("price"), 2));
+            result = s.filter(ge(member("price"), 2));
             assertEquals(result.length, 1);
             assertEquals(result.first, item2);
 
-            result = s.filter(gt(add(prop("price"), prop("vat"), 0), 2));
+            result = s.filter(gt(add(member("price"), member("vat"), 0), 2));
             assertEquals(result.length, 1);
             assertEquals(result.first, item1);
 
-            result = s.filter(gt(subtract(prop("price"), prop("vat")), 0));
+            result = s.filter(gt(subtract(member("price"), member("vat")), 0));
             assertEquals(result.length, 1);
             assertEquals(result.first, item2);
 
-            result = s.filter(gt(subtract(prop("price"), 1), 0));
+            result = s.filter(gt(subtract(member("price"), 1), 0));
             assertEquals(result.length, 1);
             assertEquals(result.first, item2);
 
@@ -222,43 +222,43 @@ package com.kemsky.filters
 
             var nested:Stream = $(obj);
 
-            result = nested.filter(eq(prop("name"), "p0"));
+            result = nested.filter(eq(member("name"), "p0"));
             assertEquals(result.length, 1);
 
-            result = nested.filter(eq(prop("name1"), undefined));
+            result = nested.filter(eq(member("name1"), undefined));
             assertEquals(result.length, 1);
 
 
-            result = nested.filter(eq(prop("item.name"), "p1"));
+            result = nested.filter(eq(member("item.name"), "p1"));
             assertEquals(result.length, 1);
 
-            result = nested.filter(eq(prop("item.name1"), undefined));
+            result = nested.filter(eq(member("item.name1"), undefined));
             assertEquals(result.length, 1);
 
 
-            result = nested.filter(eq(prop("item.item.name"), "p2"));
+            result = nested.filter(eq(member("item.item.name"), "p2"));
             assertEquals(result.length, 1);
 
-            result = nested.filter(eq(prop("item.item.name1"), undefined));
+            result = nested.filter(eq(member("item.item.name1"), undefined));
             assertEquals(result.length, 1);
 
 
-            result = nested.filter(eq(prop("item.item.item.name"), "p3"));
+            result = nested.filter(eq(member("item.item.item.name"), "p3"));
             assertEquals(result.length, 1);
 
-            result = nested.filter(eq(prop("item.item.item.name1"), undefined));
+            result = nested.filter(eq(member("item.item.item.name1"), undefined));
             assertEquals(result.length, 1);
 
 
-            result = nested.filter(eq(prop("item.item.item.item.name"), "p4"));
+            result = nested.filter(eq(member("item.item.item.item.name"), "p4"));
             assertEquals(result.length, 1);
 
-            result = nested.filter(eq(prop("item.item.item.item.name1"), undefined));
+            result = nested.filter(eq(member("item.item.item.item.name1"), undefined));
             assertEquals(result.length, 1);
 
             try
             {
-                nested.filter(eq(prop("item.item.item.item.item.name"), "p5"));
+                nested.filter(eq(member("item.item.item.item.item.name"), "p5"));
                 assertTrue(false);
             }
             catch(e:Error){}
@@ -295,8 +295,8 @@ package com.kemsky.filters
 
             var s:Stream = $(item);
 
-            assertEquals(s.filter(mapped(prop("name"), d)).length, 1);
-            assertEquals(s.filter(mapped(prop("name"), o)).length, 1);
+            assertEquals(s.filter(mapped(member("name"), d)).length, 1);
+            assertEquals(s.filter(mapped(member("name"), o)).length, 1);
 
 
             var p:Stream = $("name", "price", "vat");