Getting the value of a key in a hash whereby the key can be at a different level in the hash each time

[Pixelshifter]

Suppose I have the following two hashes (Hieradata):

hash 1:

nginx::nginx_servers:
  "${::fqdn}":
    server_name:
      - 'foo.bar.com
      -baz.bar.com
    locations:
      '@403':
        return: '403'
      '@proxyloc':
        location_cfg_append:
          proxy_pass: 'http://127.0.0.1:8088'

hash 2:

nginx::nginx_servers:
  "${::fqdn}":
    server_name:
      - 'foo.bar.com
      -baz.bar.com
    location_cfg_append:
      proxy_pass: 'http://127.0.0.1:8088'

How can I, within my Puppet-manifest, get the value from proxy_pass as dynamically as possible?

$nginx_config = lookup(nginx::nginx_servers)

And after this I wanna parse the $nginx_config but before Googling another three hours maybe someone here has had the same challenge as me before and has a solution? Thanks in advance for any help!