input: Write a function to evaluate a given string containing a numerical expression and return the result. Ensure the function handles basic arithmetic operations.
  assert eval_expr("2+3*4")==14
  assert eval_expr("(10-4)/2")==3
  assert eval_expr("7")==7
  assert eval_expr("5.5+2.5")==8
  assert eval_expr("12/3+2")==6
output: def eval_expr(expression):
      return eval(expression)