Add method str to linesegment

The method str returns the line segment coordinates as string.

linesegment.py

@@ -1,5 +1,5 @@
 #!/usr/bin/python3
-"""The linesegment module defines the class line_segment"""
+"""The linesegment module defines the class line_segment."""
 
 import point
 
@@ -12,14 +12,14 @@ class LineSegment:
         self.set_endpoint(endpoint)
     def set_startpoint(self, new_startpoint):
         """Set or change the startpoint of the line segment. If not a Point object is given
-        the startpoint gets set to a default value of Point(0,0)"""
+        the startpoint gets set to a default value of Point(0,0)."""
         self.__startpoint = new_startpoint
     def get_startpoint(self):
         """Returns the current startpoint"""
         return self.__startpoint
     def set_endpoint(self, new_endpoint):
         """Set or change the endpoint of the line segment. If not a Point object is given
-        the endpoint gets set to a default value of Point(0,0)"""
+        the endpoint gets set to a default value of Point(0,0)."""
         self.__endpoint = new_endpoint
     def get_endpoint(self):
         """Returns the current endpoint"""
@@ -29,5 +29,8 @@ class LineSegment:
         diff_x = abs(self.__startpoint.get_x() - self.__endpoint.get_x())
         diff_y = abs(self.__startpoint.get_y() - self.__endpoint.get_y())
         return ((diff_x ** 2) + (diff_y ** 2)) ** (1/2.0)
+    def str(self):
+        """Return the line segment values as string."""
+        return self.__startpoint.str() + "-->" + self.__endpoint.str()
     def draw(self):
-        """TODO: Draw the line segment in a canvas"""
+        """TODO: Draw the line segment in a canvas."""