def list_firewalls(start, attempts)
      result = execute( firewall_list_req(), start, attempts )
      firewalls = result["items"]
      firewalls.delete_if{|f| f['name'] =~ /default-allow-internal|default-ssh/}
      firewalls
    end
def list_firewalls(start, attempts)
      result = execute( firewall_list_req(), start, attempts )
      firewalls = result["items"]
      firewalls.delete_if{|f| f['name'] =~ /default-allow-internal|default-ssh/}
      firewalls
    end
Determines a list of existing Google Compute firewalls

 @param [Integer] start The time when we started code execution, it is
 compared to Time.now to determine how many further code execution
 attempts remain

 @param [Integer] attempts The total amount of attempts to execute that we
 are willing to allow

 @return [Array[Hash]] The firewalls array of hashes

 @raise [Exception] Raised if we fail determine the list of existing
 firewalls, either through errors or running out of attempts