code: def evaluate_expression(expression, vars):
      '''evaluation an expression'''
      try:
          v = eval(expression, globals(), vars)
      except NameError:
          return None
      except ZeroDivisionError:
          return None
      return f evaluate_expression(expression, vars):
      '''evaluation an expression'''
      try:
          v = eval(expression, globals(), vars)
      except NameError:
          return None
      except ZeroDivisionError:
          return None
      return v
docs: evaluation an expression