input: from typing import List
  
  
  def eval_expr(expr: str) -> float:
      """ Evaluates a string containing a numerical expression and returns the result.
      >>> eval_expr("3 + 5 * 2")
      13
      >>> eval_expr("(4 + 6) / 2")
      5.0
      """
      return eval(expr)
output:     return eval(expr)