title: Reading a grib2 message into an Iris cube
body: <p>I am currently exploring the notion of using iris in a project to read forecast grib2 files using python. </p>
  
  <p>My aim is to load/convert a grib message into an iris cube based on a grib message key having a specific value. </p>
  
  <p>I have experimented with iris-grib, which uses gribapi. Using iris-grib I have not been to find the key in the grib2 file, althrough the key is visible with 'grib_ls -w...' via the cli. 
  gribapi does the job, but I am not sure how to interface it with iris (which is what, I assume, iris-grib is for). </p>
  
  <p>I was wondering if anyone knew of a way to get a message into an iris cube based on a grib message key having a specific value. Thank you</p>