You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: pinentry.go
    path of file: ./repos/teller/vendor/github.com/twpayne/go-pinentry
    
    the code of the file until where you have to start completion: // Package pinentry provides a client to GnuPG's pinentry.
//
// See info pinentry.
// See https://www.gnupg.org/related_software/pinentry/index.html.
// See https://www.gnupg.org/documentation/manuals/assuan.pdf.
    
func (c *Client) readLine() ([]byte, error) {
	for {
		line, _, err := c.process.ReadLine()
		if err != nil {
			return nil, err
		}
		if c.logger != nil {
			c.logger.Err(err).Bytes("line", line).Msg("readLine")
		}
		switch {
		case isBlank(line):
		case isComment(line):
		case isError(line):
			return nil, newError(line)
		default:
			return line, err
		}
	}
}