code: def set_property_filter(filter_proto, name, op, value):
    
    filter_proto.Clear()
    pf = filter_proto.property_filter
    pf.property.name = name
    pf.op = op
    set_value(pf.value, value)
    return filter_proto
docs: Set property filter contraint in the given datastore.Filter proto message.
  
    Args:
      filter_proto: datastore.Filter proto message
      name: property name
      op: datastore.PropertyFilter.Operation
      value: property value
  
    Returns:
      the same datastore.Filter.
  
    Usage:
      >>> set_property_filter(filter_proto, 'foo',
      ...   datastore.PropertyFilter.EQUAL, 'a')  # WHERE 'foo' = 'a'