input: Write a function to generate and print Pascal's triangle for a given number of rows. If the number of rows is less than 1, do not print anything.
  def pascal_triangle(n):
      trow = [1]
      y = [0]
      for x in range(max(n, 0)):
          print(trow)
          trow = [l + r for l, r in zip(trow + y, y + trow)]
      return n >= 1
  
  assert pascal_triangle(5) == True
  assert pascal_triangle(0) == True
  assert pascal_triangle(3) == True
  assert pascal_triangle(-1) == True
  assert pascal_triangle(1) == True
output: def pascal_triangle(n):
      if n < 1:
          return False
      trow = [1]
      y = [0]
      for x in range(n):
          print(trow)
          trow = [l + r for l, r in zip(trow + y, y + trow)]
      return True