create some block tests and the expression

lib/ast/block_expression.rb

@@ -0,0 +1,26 @@
+module Ast
+  class BlockExpression < Expression
+    attr_reader  :call_exp, :args , :body_exp
+
+    def initialize call_exp, args , body_exp
+      @call_exp = call_exp.to_sym
+      @args = args
+      @body_exp =  body_exp
+    end
+
+    def attributes
+      [:call_exp, :args , :body_exp]
+    end
+
+    def inspect
+      self.class.call_exp + ".new(" + call_exp.inspect + ", ["+
+        args.collect{|m| m.inspect }.join( ",") + "] ," + body_exp.inspect  + ")"
+    end
+    def to_s
+      "#{call_exp}(" + args.join(",") + ")"
+    end
+    def attributes
+      [:call_exp , :args , :body_exp]
+    end
+  end
+end