input: 
  def solve_linear_equation_system(a: float, b: float, c: float) -> (float, float):
      """ Solve a linear equation system of the form: ax + by = c.
      >>> solve_linear_equation_system(2, 1, 4)
      (2.0, 2.0)
      """
  
output:     if a == 0 and b == 0:
          raise ValueError("The system has no unique solution.")
      elif a == 0:
          return (0.0, c / b)
      elif b == 0:
          return (c / a, 0.0)
      else:
          return (c / a, 0.0)