code: func (c *Container) Next() bool {
  	if c.err != nil {
  		return false
  	}
  	var b Block
  	c.err = b.readFrom(c.blockData)
  	if c.err == nil {
  		c.block = &b
  		return true
  	}
  	return false
  }
docs: // Next advances the Container to the next CRAM block. It returns false
  // when the data ends, either by reaching the end of the container or
  // encountering an error.