diff --git a/lib/peach.rb b/lib/peach.rb
index c1e8aa9..0271fed 100644
--- a/lib/peach.rb
+++ b/lib/peach.rb
@@ -52,3 +52,27 @@ def pselect(pool = nil, &b)
     result
   end
 end
+
+class File
+  def _peach_run(pool = nil, &b)
+    pool ||= $peach_default_threads || count
+    pool = 1 unless pool >= 1
+    div = (count/pool).to_i # should already be integer
+    div = 1 unless div >= 1 # each thread better do something!
+
+    threads = []
+    each_slice(div).with_index do |slice, idx|
+      threads << Thread.new(slice) do |thread_slice|
+        yield thread_slice, idx, div
+      end
+    end
+    threads.each{|t| t.join }
+    self
+  end
+
+  def peach_line(pool = nil, &b)
+    _peach_run(pool) do |thread_slice, idx, div|
+      thread_slice.each{|elt| yield elt}
+    end
+  end
+end
diff --git a/test/data.txt b/test/data.txt
new file mode 100644
index 0000000..469c856
--- /dev/null
+++ b/test/data.txt
@@ -0,0 +1,16 @@
+1
+2
+3
+4
+5
+6
+7
+8
+9
+10
+11
+12
+13
+14
+15
+16
diff --git a/test/peach_test.rb b/test/peach_test.rb
index 4a9c695..583c8c9 100644
--- a/test/peach_test.rb
+++ b/test/peach_test.rb
@@ -43,4 +43,18 @@ class PeachTest < Test::Unit::TestCase
     end
   end
 
+  [:peach_line].each do |f|
+    context "#{f}" do
+      normal_f = f.to_s[1..-1].to_sym
+
+      setup do
+        @data = File.open(File.join(File.dirname(__FILE__), 'data.txt'), 'r')
+        @block = lambda{|i| i.to_i**2}
+      end
+      should "return the same result as #{normal_f}" do
+        assert_equal @data.send(normal_f, &@block),
+          @data.send(f, 100, &@block)
+      end
+    end
+  end
 end