input: def numerical_expression_eval(expression: str) -> float:
      """
      Evaluate a given string containing a numerical expression and return the result.
      
      >>> numerical_expression_eval("2+2")
      4.0
      >>> numerical_expression_eval("10*2-4")
      16.0
      >>> numerical_expression_eval("2**3")
      8.0
      """
      return eval(expression)
output:     return eval(expression)