input: Write a function to format a given amount of money with a specified symbol.
  assert format_money(95.50, '€') == '€95.50'
  assert format_money(100, '$') == '$100.00'
  assert format_money(0.5, '£') == '£0.50'
output: def format_money(amount, symbol):
      return f"{symbol}{amount:.2f}"