input: from typing import List
  
  def pascal_triangle(n: int) -> None:
      """
      Print Pascal's triangle for a given number of rows.
      
      >>> pascal_triangle(5)
      [1]
      [1, 1]
      [1, 2, 1]
      [1, 3, 3, 1]
      [1, 4, 6, 4, 1]
      """
output:     if n <= 0:
          return
  
      triangle = [[1]]
      for i in range(1, n):
          row = [1]
          for j in range(1, i):
              row.append(triangle[i-1][j-1] + triangle[i-1][j])
          row.append(1)
          triangle.append(row)
  
      for row in triangle:
          print(row)