code: def validate_allowed_values(allowed_values, value):
      
      # ignore CFNParameter, troposphere handles these for us
      if not allowed_values or isinstance(value, CFNParameter):
          return True
  
      return value in allowed_values
docs: Support a variable defining which values it allows.
  
      Args:
          allowed_values (Optional[list]): A list of allowed values from the
              variable definition
          value (obj): The object representing the value provided for the
              variable
  
      Returns:
          bool: Boolean for whether or not the value is valid.