```ruby
require 'puppetx/l23_network_scheme'

Puppet::Parser::Functions::newfunction(:get_nic_passthrough_whitelist, :type => :rvalue, :arity => 1, :doc => <<-EOS
    This function gets pci_passthrough_whitelist mapping from transformations
    Returns NIL if no transformations with this provider found or list
    ex: pci_passthrough_whitelist('sriov')
    EOS
  ) do |argv|
  provider = argv[0].to_s.upcase

  cfg = L23network::Scheme.get_config(lookupvar('l3_fqdn_hostname'))
  transformations = cfg[:transformations]
  rv = []

  transformations.each do |transform|
    if transform[:provider].to_s.upcase == provider and\
       transform[:action] == "add-port" and\
       transform[:vendor_specific][:physnet]
      rv.push({"devname" => transform[:name], "physical_network" => transform[:vendor_specific][:physnet]})
    end
  end

  rv unless rv.empty?
end

# vim: set ts=2 sw=2 et :
```

Add workaround for import puppetx::* from parser functions
user
```ruby
begin
  require 'puppetx/l23_network_scheme'
rescue LoadError => e
  rb_file = File.join(File.dirname(__FILE__),'..','..','..','puppetx','l23_network_scheme.rb')
  load rb_file if File.exists?(rb_file) or raise e
end
#
Puppet::Parser::Functions::newfunction(:get_nic_passthrough_whitelist, :type => :rvalue, :arity => 1, :doc => <<-EOS
    This function gets pci_passthrough_whitelist mapping from transformations
    Returns NIL if no transformations with this provider found or list
    ex: pci_passthrough_whitelist('sriov')
    EOS
  ) do |argv|
  provider = argv[0].to_s.upcase

  cfg = L23network::Scheme.get_config(lookupvar('l3_fqdn_hostname'))
  transformations = cfg[:transformations]
  rv = []

  transformations.each do |transform|
    if transform[:provider].to_s.upcase == provider and\
       transform[:action] == "add-port" and\
       transform[:vendor_specific][:physnet]
      rv.push({"devname" => transform[:name], "physical_network" => transform[:vendor_specific][:physnet]})
    end
  end

  rv unless rv.empty?
end

# vim: set ts=2 sw=2 et :
```
assistant