old_contents: #!/usr/bin/env python
  from math import pi, sin, cos
  
  from .trajectory import Trajectory
  
  
  class LissajousTrajectory(object, Trajectory):
      def __init__(self, A, B, a, b, period, delta=pi/2):
          Trajectory.__init__(self)
          self.A = A
          self.B = B
          self.a = a
          self.b = b
          self.period = period
          self.delta = delta
  
      def get_position_at(self, t):
          super(LissajousTrajectory, self).get_position_at(t)
          self.position.x = self.A * sin(2 * pi * t * self.a / self.period + self.delta)
          self.position.y = -self.B * sin(2 * pi * t * self.b / self.period)
  
          return self.position
  
      def get_name(self):
          return str(LissajousTrajectory.__name__).replace('Trajectory', '').lower()
  
new_contents: #!/usr/bin/env python
  from math import pi, sin
  
  from .trajectory import Trajectory
  
  
  class LissajousTrajectory(object, Trajectory):
      def __init__(self, A, B, a, b, period, delta=pi/2):
          Trajectory.__init__(self)
          self.A = A
          self.B = B
          self.a = a
          self.b = b
          self.period = period
          self.delta = delta
  
      def get_position_at(self, t):
          super(LissajousTrajectory, self).get_position_at(t)
          self.position.x = self.A * sin(2 * pi * t * self.a / self.period + self.delta)
          self.position.y = self.B * sin(2 * pi * t * self.b / self.period)
  
          return self.position
  
      def get_name(self):
          return str(LissajousTrajectory.__name__).replace('Trajectory', '').lower()
  
subject: Fix wrong formula for y position