Net::FTP#gettextfile

# File tmp/rubies/ruby-3.0.5/lib/net/ftp.rb, line 804
def gettextfile(remotefile, localfile = File.basename(remotefile),
                &block) # :yield: line
  f = nil
  result = nil
  if localfile
    f = File.open(localfile, "w")
  elsif !block_given?
    result = String.new
  end
  begin
    retrlines("RETR #{remotefile}") do |line, newline|
      l = newline ? line + "\n" : line
      f&.print(l)
      block&.(line, newline)
      result&.concat(l)
    end
    return result
  ensure
    f&.close
  end
end