public void addChildScope(Scope child){
  if (childScopes == null) {
    childScopes=new ArrayList<Scope>();
  }
  childScopes.add(child);
  child.setParentScope(this);
}

public void addChildScope ( Scope child ) { if ( childScopes == null ) { childScopes = new ArrayList < Scope > ( ) ; } childScopes . add ( child ) ; child . setParentScope ( this ) ; }
add a scope to our list of child scopes . sets the child ' s parent scope to this scope .
