code: Expression getVariable( String name ) {
          for( int i = state.stackIdx - 1; i >= 0; i-- ) {
              Expression variable = state.stack.get( i ).getVariable( name );
              if( variable != null ) {
                  return variable;
              }
          }
          if( name.equals( "@arguments" ) ) {
              for( int i = state.stackIdx - 1; i >= 0; i-- ) {
                  Scope scope = state.stack.get( i );
                  if( scope.parameters != null ) {
                      Operation params = new Operation( scope.mixin, ' ' );
                      for( Expression expr : scope.parameters.values() ) {
                          if( expr.getClass() == Operation.class && scope.parameters.size() == 1 ) {
                              return expr;
                          }
                          params.addOperand( expr );
                      }
                      return params;
                  }
              }
          }
          return null;
      }
docs: Get a variable expression from the current stack
  
  @param name
  the name of the variable starting with @
  @return the expression or null if not found