added default output of twhois command if no usernames are specified

bin/twhois

@@ -2,25 +2,30 @@
 require 'rubygems'
 require 'twhois'
 
-ARGV.each do |username|
-  user = Twhois.lookup(username)
-  if user
-    puts "@#{user.screen_name}:"
-    puts "  Name: #{user.name}"
-    puts "  URL: #{user.url}" if user.url
-    puts "  Location: #{user.location}" if user.location
-    puts "  Description: #{user.description}" if user.description
-    puts "  Followers: #{user.followers_count}"
-    puts "  Following: #{user.friends_count}"
-    puts "  Tweets: #{user.statuses_count}"
-    puts "  Last Tweet (#{user.status['created_at']}):"
-    puts "    #{user.status['text']}"
-    puts "  Timezone: #{user.time_zone}" if user.time_zone
-    puts "  Joined On: #{user.created_at}"
-    puts "  Profile Picture: #{user.profile_image_url}"
-    puts "  Private Account: #{user.protected ? "Yes" : "No"}"
-  else
-    puts "@#{username}:"
-    puts "  Not Found"
+if ARGV.size > 0
+  ARGV.each do |username|
+    user = Twhois.lookup(username)
+    if user
+      puts "@#{user.screen_name}:"
+      puts "  Name: #{user.name}"
+      puts "  URL: #{user.url}" if user.url
+      puts "  Location: #{user.location}" if user.location
+      puts "  Description: #{user.description}" if user.description
+      puts "  Followers: #{user.followers_count}"
+      puts "  Following: #{user.friends_count}"
+      puts "  Tweets: #{user.statuses_count}"
+      puts "  Last Tweet (#{user.status['created_at']}):"
+      puts "    #{user.status['text']}"
+      puts "  Timezone: #{user.time_zone}" if user.time_zone
+      puts "  Joined On: #{user.created_at}"
+      puts "  Profile Picture: #{user.profile_image_url}"
+      puts "  Private Account: #{user.protected ? "Yes" : "No"}"
+    else
+      puts "@#{username}:"
+      puts "  Not Found"
+    end
   end
+else
+  puts "Usage: twhois username [another_user] [yet_another]"  
 end
+