input: Write a function that generates and prints the rows of Pascal's triangle for a given number of rows. The function should take an integer `n` as input, representing the number of rows to print. If `n` is less than 1, the function should simply return without printing any rows.
  
  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)==False
  assert pascal_triangle(-3)==False
  assert pascal_triangle(1)==True
  assert pascal_triangle(10)==True
output: def pascal_triangle(n):
      if n < 1:
          return
      trow = [1]
      y = [0]
      for x in range(n):
          print(trow)
          trow = [l + r for l, r in zip(trow + y, y + trow)]