code: def set_property(property_map, name, value, exclude_from_indexes=None):
    
    set_value(property_map[name], value, exclude_from_indexes)
docs: Set property value in the given datastore.Property proto message.
  
    Args:
      property_map: a string->datastore.Value protobuf map.
      name: name of the property.
      value: python object or datastore.Value.
      exclude_from_indexes: if the value should be exclude from indexes. None
          leaves indexing as is (defaults to False if value is not a Value message).
  
    Usage:
      >>> set_property(property_proto, 'foo', u'a')
  
    Raises:
      TypeError: if the given value type is not supported.