input: from typing import Any
  
  
  def eval_expr(expr: str) -> Any:
      """Evaluate a given string containing a numerical expression and return the result.
      >>> eval_expr("2 + 3")
      5
      >>> eval_expr("10 - 5")
      5
      >>> eval_expr("4 * 6")
      24
      >>> eval_expr("9 / 3")
      3.0
      """
      return eval(expr)
output:     return eval(expr)