code: def radiansBetween(self, other):
          '''
          :param: other - Line subclass
          :return: float
  
          Returns the angle measured between two lines in radians
          with a range of [0, 2 * math.pi].
  
          '''
          # a dot b = |a||b| * cos(theta)
          # a dot b / |a||b| = cos(theta)
          # cos-1(a dot b / |a||b|) = theta
  
          # translate each line so that it passes through the origin and
          # produce a new point whose distance (magnitude) from the
          # origin is 1.
          #
  
          a = Point.unit(self.A, self.B)
          b = Point.unit(other.A, other.B)
  
          # in a perfect world, after unit: |A| = |B| = 1
          # which is a noop when dividing the dot product of A,B
          # but sometimes the lengths are different.
          #
          # let's just assume things are perfect and the lengths equal 1.
  
          return math.acos(a.dot(b)f radiansBetween(self, other):
          '''
          :param: other - Line subclass
          :return: float
  
          Returns the angle measured between two lines in radians
          with a range of [0, 2 * math.pi].
  
          '''
          # a dot b = |a||b| * cos(theta)
          # a dot b / |a||b| = cos(theta)
          # cos-1(a dot b / |a||b|) = theta
  
          # translate each line so that it passes through the origin and
          # produce a new point whose distance (magnitude) from the
          # origin is 1.
          #
  
          a = Point.unit(self.A, self.B)
          b = Point.unit(other.A, other.B)
  
          # in a perfect world, after unit: |A| = |B| = 1
          # which is a noop when dividing the dot product of A,B
          # but sometimes the lengths are different.
          #
          # let's just assume things are perfect and the lengths equal 1.
  
          return math.acos(a.dot(b))
docs: :param: other - Line subclass
          :return: float
  
          Returns the angle measured between two lines in radians
          with a range of [0, 2 * math.pi].