input: Write a function that takes a string containing a numerical expression and returns the result by evaluating the expression. The function should use Python's built-in `eval` function to compute the result. If the input string is not a valid numerical expression, the function should raise an appropriate exception.
  assert eval_expr("2 + 2")==4
  assert eval_expr("10 - 5")==5
  assert eval_expr("3 * 4")==12
  assert eval_expr("12 / 2")==6.0
  assert eval_expr("10 % 3")==1
output: def eval_expr(expression):
      try:
          return eval(expression)
      except:
          raise ValueError("Invalid numerical expression")