Show members of Datagroup - PowerShell

LocalLB.Class.get_address_class_member isn't a method in the API. Where did you find a reference to it? The call to get_address_class will return an array of structures containing the name and members for each class requested. Here's some code to get you started

$addressClassA = (Get-F5.iControl).LocalLBClass.get_address_class_list();
$ClassInfoA = (Get-F5.iControl).LocalLBClass.get_address_class($addressClassA);
foreach($class in $ClassInfoA) {
  $name = $class.name;
  Write-Host "Class: $name";
  $members = $class.members;
  foreach($member in $members) {
    Write-Host "  $member";
  }
}

Hope this helps...