input: Write a function to draw a right-angled triangle using asterisks.
  assert drawTriangle(3) == '*
  **
  ***\n'
  assert drawTriangle(1) == '*\n'
  assert drawTriangle(5) == '*
  **
  ***
  ****
  *****\n'
output: def drawTriangle(n):
      return ''.join('*' * i + '\n' for i in range(1, n + 1))