CGI#header

# File tmp/rubies/ruby-3.4.1/lib/cgi/core.rb, line 160
def http_header(options='text/html')
  if options.is_a?(String)
    content_type = options
    buf = _header_for_string(content_type)
  elsif options.is_a?(Hash)
    if options.size == 1 && options.has_key?('type')
      content_type = options['type']
      buf = _header_for_string(content_type)
    else
      buf = _header_for_hash(options.dup)
    end
  else
    raise ArgumentError.new("expected String or Hash but got #{options.class}")
  end
  if defined?(MOD_RUBY)
    _header_for_modruby(buf)
    return ''
  else
    buf << EOL    # empty line of separator
    return buf
  end
end