fix local assignment

was missing a method that got lost in copy/paste
also renaming to get guard to pick up tests

lib/ruby/assignment.rb

@@ -0,0 +1,48 @@
+module Ruby
+
+  class Assignment < Statement
+    attr_reader :name , :value
+    def initialize(name , value )
+      @name , @value = name , value
+    end
+
+    def to_vool()
+      raise "not named left #{name.class}" unless name.is_a?(Symbol)
+      case value
+      when Named , Constant
+        return copy
+      when SendStatement
+        return normalize_send
+      else
+        raise "unsupported right #{value}"
+      end
+    end
+
+    def copy(value = nil)
+      value ||= @value
+      self.vool_brother.new(name,value)
+    end
+
+    def normalize_send
+      statements = value.to_vool
+      return copy( statements ) if statements.is_a?(Vool::SendStatement)
+      assign = statements.statements.pop
+      statements << copy(assign)
+      statements
+    end
+
+    def to_s(depth = 0)
+      at_depth(depth , "#{@name} = #{@value}")
+    end
+
+  end
+
+  class IvarAssignment < Assignment
+
+  end
+
+  class LocalAssignment < Assignment
+
+  end
+
+end