| Read the contents of a GRIB2 file. 
    Parameters:
        filename- name of GRIB2 file (default, gribmsg=False) or binary string 
          representing a grib message (if gribmsg=True).Returns:a list of Grib2Message instances representing all of the 
          grib messages in the file.  Messages with multiple fields are 
          split into separate messages (so that each Grib2Message instance contains just one data 
          field). The metadata in each GRIB2 message can be accessed via Grib2Message instance variables, the actual data
          can be read using Grib2Message.data, and the lat/lon values of the
          grid can be accesses using Grib2Message.grid. If there is only one grib 
          message, just the Grib2Message instance is returned, instead of a 
          list with one element. |