added useless alias for yapm command in order to map to yap

main.py

@@ -4,6 +4,10 @@
 
 if __name__ == '__main__':
     args = parser.parse_arguments()
+
+    if not args.packages:
+        parser.print_help()
+        exit()
 
     command = get_command(args.command)
     packages = args.packages

snapcraft.yaml

@@ -14,5 +14,6 @@ parts:
     source: .
 
 apps:
-  yapm:
-    command: main.py
+  yap:
+    command: main.py
+    aliases: [yap]

yap/arguments/parser.py

@@ -17,9 +17,16 @@ def _get_real_parser(self):
 
     def parse(self):
         return self._get_real_parser().parse_args()
+
+    def print_help(self):
+        self._get_real_parser().print_help()
 
 
 def parse_arguments():
     parser = Parser()
     args = parser.parse()
     return args
+
+def print_help():
+    parser = Parser()
+    parser.print_help()