code: func (out *DataOutputImpl) WriteVLong(i int64) error {
  	assert(i >= 0)
  	return out.writeNegativeVLong(i)
  }
docs: /*
  Writes an long in a variable-length format. Writes between one and
  none bytes. Smaller values take fewer bytes. Negative number are not
  supported.
  
  The format is described further in WriteVInt().
  */