input: Write a function to generate and print a Pascal triangle with the given number of rows. The function should take an integer 'n' as input and print the Pascal triangle accordingly. If the input 'n' is 0, the function should print nothing.
  assert PascalTriangle(5)==None
  assert PascalTriangle(0)==None
  assert PascalTriangle(3)==None
  assert PascalTriangle(1)==None
  assert PascalTriangle(7)==None
output: def PascalTriangle(n):
      if n == 0:
          return
      for i in range(n):
          row = [1] * (i + 1)
          for j in range(1, i):
              row[j] = prev_row[j - 1] + prev_row[j]
          prev_row = row
          print(' '.join(map(str, row)).center(n * 3))