input: Write a function to print a pattern of stars that starts with a triangle of increasing height and then a triangle of decreasing height. The function should be named `print_star_pattern`.
  assert print_star_pattern()=="""  
  *  
  **  
  ***  
  ****  
  *****  
  ****  
  ***  
  **  
  *  
  """
  assert print_star_pattern()=="""  
  *  
  **  
  ***  
  ****  
  *****  
  ****  
  ***  
  **  
  *  
  """
output: def print_star_pattern():
      result = ""
      for i in range(1, 6):
          result += "*" * i + "\n"
      for i in range(4, 0, -1):
          result += "*" * i + "\n"
      return result