Turtlegraphics Procedures and Functions

 Back         Moves turtle backward by the given distance
 ClearScreen  Clears the active window and homes turtle
 Forwd        Moves turtle forward by the given distance
 HideTurtle   Hides turtle
 Home         Puts turtle in its home position
 NoWrap       Disables "wrapping" for turtle
 PenDown      Puts turtle's pen "down" so that any movement of turtle results
              in drawing
 PenUp        Puts turtle's pen "up" so that turtle can be moved without
              drawing
 SetHeading   Turns turtle to the specified angle
 SetPenColor  Sets the color used for turtle's pen
 SetPosition  Moves turtle to the given coordinates without drawing a line
 ShowTurtle   Makes turtle visible
 TurnLeft     Turns turtle's heading to the left (counter-clockwise)
 TurnRight    Turns turtle's heading to the right (clockwise)
 TurtleDelay  Sets a delay between each step of turtle
 TurtleWindow Defines an area of the screen as the active turtlegraphics
              screen
  Wrap        Forces wraparound when turtle attempts to move past the
              boundaries of the active window

 Heading     Returns the current heading of turtle
 TurtleThere Tests if turtle is visible and in the active window
 XCor        Returns the current X-coordinate of turtle
 YCor        Returns the current Y-coordinate of turtle

 GRAPH3.TPU