code: function markDuplicateVariableNames (row, i, rows) {
    var ast = row[kAst]
  
    var scope = scan.scope(ast)
    if (scope) {
      scope.forEach(function (binding, name) {
        binding[kShouldRename] = rows.usedGlobalVariables.has(name)
        rows.usedGlobalVariables.add(name)
      })
    }
  }
docs: Mark module variables that collide with variable names from other modules so we can rewrite them.