smaps: Add __len__ method

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
diff --git a/procfs/procfs.py b/procfs/procfs.py
index dd9778d..21d2143 100755
--- a/procfs/procfs.py
+++ b/procfs/procfs.py
@@ -777,6 +777,9 @@
 		self.entries.append(smaps_lib(lines))
 		return line
 
+	def __len__(self):
+		return len(self.entries)
+
 	def __getitem__(self, index):
 		return self.entries[index]