code: void parseLazy( CssFormatter formatter ) {
          if( lazyImports != null ) {
              HashMap<String, Expression> vars = variables;
              formatter.addVariables( vars );
              for( int i = 0; i < lazyImports.size(); i++ ) {
                  LazyImport lazyImport = lazyImports.get( i );
                  String filename = lazyImport.stringValue( formatter );
                  baseURL = lazyImport.getBaseUrl();
                  variables = lazyImport.getVariables();
                  rulesIdx = lazyImport.lastRuleBefore() == null ? 0 : rules.indexOf( lazyImport.lastRuleBefore() ) + 1 ;
                  importFile( this, filename );
              }
              formatter.removeVariables( vars );
              variables = vars;
          }
      }
docs: If there are some imports with variables then this will parse after a formatter if available.
  @param formatter the formatter to evaluate variables