Fixed typos and syntax errors.

example_11.md

@@ -102,7 +102,7 @@ class PointCloudTransformer:
         """
         while not rospy.is_shutdown():
             try:
-                new_cloud = self.listener.transformPointCloud("/base_link" ,msg)
+                new_cloud = self.listener.transformPointCloud("base_link" ,msg)
                 return new_cloud
                 if new_cloud:
                     break
@@ -191,7 +191,7 @@ Utilize the `transform_pointcloud` function to transform the points in the `Poin
 ```python
 while not rospy.is_shutdown():
         try:
-            new_cloud = self.listener.transformPointCloud("/base_link" ,msg)
+            new_cloud = self.listener.transformPointCloud("base_link" ,msg)
             return new_cloud
             if new_cloud:
                 break

example_4.md

@@ -42,7 +42,7 @@ class Balloon():
 		"""
 		self.publisher = rospy.Publisher('balloon', Marker, queue_size=10)
 		self.marker = Marker()
-		self.marker.header.frame_id = '/base_link'
+		self.marker.header.frame_id = 'base_link'
 		self.marker.header.stamp = rospy.Time()
 		self.marker.type = self.marker.SPHERE
 		self.marker.id = 0
@@ -103,7 +103,7 @@ This section of code defines the talker's interface to the rest of ROS. `pub = r
 
 ```python
 self.marker = Marker()
-self.marker.header.frame_id = '/base_link'
+self.marker.header.frame_id = 'base_link'
 self.marker.header.stamp = rospy.Time()
 self.marker.type = self.marker.SPHERE
 ```

src/marker.py

@@ -23,7 +23,7 @@ class Balloon():
 
 		# Set the frame ID and type.  The frame ID is the frame in which the position of the marker
 		# is specified.  The type is the shape of the marker, detailed on the wiki page
-		self.marker.header.frame_id = '/base_link'
+		self.marker.header.frame_id = 'base_link'
 		self.marker.header.stamp = rospy.Time()
 		self.marker.type = self.marker.SPHERE
 

src/pointcloud_transformer.py

@@ -80,7 +80,7 @@ class PointCloudTransformer:
             try:
                 # run the transformPointCloud() function to change the referene frame
                 # to the base_link
-                new_cloud = self.listener.transformPointCloud("/base_link" ,msg)
+                new_cloud = self.listener.transformPointCloud("base_link" ,msg)
                 return new_cloud
                 if new_cloud:
                     break

src/scan_filter.py

@@ -60,7 +60,7 @@ if __name__ == '__main__':
 	rospy.init_node('scan_filter')
 
 	# Instantiate the ScanFilter class
-	Scanfilter()
+	ScanFilter()
 
 	# Give control to ROS.  This will allow the callback to be called whenever new
 	# messages come in.  If we don't put this line in, then the node will not work,