input: Write a python function to evaluate a mathematical expression given as a string using the eval function.
  assert eval_expr("2 * (3 + 4)") == 14
  assert eval_expr("10 / 2 + 3") == 8.0
  assert eval_expr("5 - 1 * 4") == 1
output: def eval_expr(expression: str) -> float:
      return eval(expression)