knownfiles = ['/etc/mime.types', '/etc/httpd/mime.types',
    '/etc/httpd/conf/mime.types', '/etc/apache/mime.types',
    '/etc/apache2/mime.types', '/usr/local/etc/httpd/conf/mime.types',
    '/usr/local/lib/netscape/mime.types',
    '/usr/local/etc/httpd/conf/mime.types', '/usr/local/etc/mime.types']
How to set the content type header in response for a particular file type in Pyramid web framework