diff --git a/python/trx/change_sign_of_dict_elements.py b/python/trx/change_sign_of_dict_elements.py
new file mode 100644
index 0000000..fd7c585
--- /dev/null
+++ b/python/trx/change_sign_of_dict_elements.py
@@ -0,0 +1,30 @@
+"""
+Embedded Python Blocks:
+
+Each this file is saved, GRC will instantiate the first class it finds to get
+ports and parameters of your block. The arguments to __init__  will be the
+parameters. All of them are required to have default values!
+"""
+
+from gnuradio import gr
+from pmt import *
+
+class change_sign_of_dict_elements(gr.basic_block):
+    def __init__(self):  # only default arguments here
+        gr.basic_block.__init__(
+            self,
+            name='Change sign of elts in dict',
+            in_sig=[],
+            out_sig=[]
+        )
+        self.message_port_register_in(intern("dict_in"))
+        self.message_port_register_out(intern("dict_out"))
+        self.set_msg_handler(intern("dict_in"), self.change_sign)
+
+    def change_sign(self, msg):
+        if is_dict(msg):
+            d = to_python(msg)
+            #print d
+            for key, value in d.items():
+                d[key] *= -1
+            self.message_port_pub(intern("dict_out"), to_pmt(d))