grc/transmitter/gsm_gen_test_ab.xml

<?xml version="1.0"?>
<block>
  <name>Gen Test AB</name>
  <key>gsm_gen_test_ab</key>
  <import>import grgsm</import>
  <make>grgsm.gen_test_ab()</make>

  <sink>
    <name>bursts_in</name>
    <type>message</type>
    <optional>1</optional>
  </sink>

  <source>
    <name>bursts_out</name>
    <type>message</type>
    <optional>1</optional>
  </source>
</block>