Dargon Curve Python

The dragon curve fractal can be defined in a Lindenmayer System. The method can be easily acquire in the math websites or in wikipedia. Here is a sample:

• angle 90°
• initial string FX
• string rewriting rules
  • X ↦ X+YF+
  • Y ↦ −FX−Y 
  
   This can be describe as:
  
  • start with a base segment
  • replace each segment by 2 segment with a right angle and a rotation of 45 degrees
  
  
  Here is a further explanation 
  
  • + = turn right
  • - = turn left 
  • F = go forward 
  • FX = initial string 
  • X = X+YF+
  • Y = -FX-Y
  
  In our python we will control the generation through some inputs
  
  
  •  length, =  is the distance the turtle function will travel (the drawn line)
  •  angle, = angle of the turtles rotation
  • level, = this is the iteration level
  • first_state = this is the L-systems starting description basically FX
  •  tar1, =character to replace the each iteration
  • tar2,  = character to replace the each iteration
  • replace, = the character/value to replace with
  • replace2 = the character/value to replace with
  
  
   Here we start an initial state of FX. Remember we a rule that states that every X in the list is replace with X+YF+. We get F(X+YF+) or FX+YF+. This basically means Move Forward -> Turn Right -> Move Forward -> Turn Right. This creates a corner 
  
  In the next iteration we replace all Y characters with -FX-Y.
   our first corner was FX+YF++-FX-Y.F+
  
  Here is a value in 5 level:
  FX+YF++-FX-YF++-FX+YF+--FX-YF++-FX+YF++-FX-YF+--FX+YF+--FX-YF++-FX+YF++-FX-YF++-FX+YF+--FX-YF+--FX+YF++-FX-YF+--FX+YF+--FX-YF+
  
  Here is a piece of the code :
  # this means all the names in the turtle module will be available to us
  from turtle import *
  
  # in here we try and state the varaibles which are going to be used for our loops
  def DragonCurve(length, angle, level,first_state, tar1,replace, tar2, replace2):
  
  constant = first_state
  
  for count in range(level):
  constant2 = ''
  for char in constant:
  

  if char == tar1:
  

  constant2 +=replace

  elif char == tar2:
  

  constant2 +=replace2

  else:
  

  constant2 +=char

  constant = constant2
  
  
  # this will try and draw our dragon curve based on the value taken from previous loop
  for char in constant:
  if char =='F':
  

  forward(length)

  elif char == '+':
  

  right(angle)

  elif char =='-':
  

  left(angle)
  # this is a turtle command that takes the speed of our drawing
  speed(50)
  hideturtle()
  # this will start up our commands
  DragonCurve(10,90,10,'FX+FX+','X','X+YF','Y','FX-Y')