add an example usage message and switch to using RawTextHelpFormatter so that...

add an example usage message and switch to using RawTextHelpFormatter so that the newlines are preserved in our description (#11)

gridded_glm/libexec/_minute_gridder.py

@@ -2,6 +2,15 @@
 # Based on https://github.com/deeplycloudy/glmtools/blob/master/examples/grid/make_GLM_grids.py
 
 parse_desc = """Create one minute NetCDF4 grids (and, optionally, AWIPS-compatible tiles) from GLM flash data.
+
+Example usage:\n
+    cspp-geo-gglm.sh \\
+        --goes-sector conus \\
+        --create-tiles \\
+        -vv \\
+        OR_GLM-L2-LCFA_G17_s20182750032000_e20182750032200_c20182750032225.nc \\
+        OR_GLM-L2-LCFA_G17_s20182750032200_e20182750032400_c20182750032426.nc \\
+        OR_GLM-L2-LCFA_G17_s20182750032400_e20182750033000_c20182750033025.nc
 """
 
 import numpy as np
@@ -26,16 +35,18 @@ log = logging.getLogger(__name__)
 
 def create_parser():
     import argparse
-    parser = argparse.ArgumentParser(description=parse_desc)
+    parser = argparse.ArgumentParser(description=parse_desc, formatter_class=argparse.RawTextHelpFormatter) # RawTextHelpFormatter preserves our newlines in the example usage message
     parser.add_argument('-v', '--verbose', dest='verbosity', action="count", default=0,
-                        help='each occurrence increases verbosity 1 level through ERROR-WARNING-INFO-DEBUG (default: ERROR)')
+                        help="each occurrence increases verbosity 1 level through ERROR-WARNING-INFO-DEBUG\n"
+                             "(default: ERROR)")
     parser.add_argument('-l', '--log', dest="log_fn", default=None,
-                        help="specify a log filename. (default: print to screen).")
+                        help="specify a log filename.\n"
+                             "(default: print to screen).")
     parser.add_argument('-o', '--output-dir', metavar='OUTPUT_DIR',
                         default=os.getcwd(), help="output directory (default: use current directory)")
     parser.add_argument('--goes-sector', default="full", choices=['full', 'conus', 'meso'],
-                        help="If sector is meso, ctr_lon and ctr_lat "
-                             "are interpreted as the ctr_x and ctr_y of the fixed grid."
+                        help="If sector is meso, ctr_lon and ctr_lat \n"
+                             "are interpreted as the ctr_x and ctr_y of the fixed grid.\n"
                              "(default: full)")
     parser.add_argument("-t", "--create-tiles", default=False, action='store_true',
                         help="create AWIPS-compatible tiles (default: off)")