old_contents: module.exports = function(grunt) {
  
      grunt.initConfig({
          pkg: grunt.file.readJSON('package.json'),
          simplemocha: {
              options: {
                  globals: ['expect'],
                  timeout: 3000,
                  ignoreLeaks: false,
                  ui: 'bdd'
              },
              all: { src: ['tests/*.js'] }
          },
          xo: {
               target: ['lib/*']
          },
          jsdoc2md: {
              oneOutputFile: {
                  src: 'lib/*.js',
                  dest: 'doc/api.md'
              }
          },
          concat: {
              options: {
                  separator: '\n'
              },
              dist: {
                  src: ['doc/README.header.md', 'doc/api.md', 'doc/README.footer.md'],
                  dest: 'README.md'
              }
          },
          shell: {
              coveralls: {
                  command: 'node_modules/.bin/nyc node_modules/.bin/mocha tests/*.js && node_modules/.bin/nyc report --reporter=text-lcov | node_modules/.bin/coveralls --force'
              },
              purgebadges: {
                  command: 'node_modules/.bin/camo-purge'
              }
          }
      });
  
      grunt.loadNpmTasks('grunt-xo');
      grunt.loadNpmTasks('grunt-simple-mocha');
      grunt.loadNpmTasks('grunt-contrib-concat');
      grunt.loadNpmTasks('grunt-shell');
      grunt.registerTask('test', ['xo', 'shell:coveralls', 'simplemocha', 'shell:purgebadges']);
  
      grunt.loadNpmTasks('grunt-jsdoc-to-markdown');
      grunt.registerTask('doc', ['jsdoc2md', 'concat']);
  };
  
new_contents: module.exports = function(grunt) {
  
      grunt.initConfig({
          pkg: grunt.file.readJSON('package.json'),
          simplemocha: {
              options: {
                  globals: ['expect'],
                  timeout: 3000,
                  ignoreLeaks: false,
                  ui: 'bdd'
              },
              all: { src: ['tests/*.js'] }
          },
          xo: {
               target: ['lib/*']
          },
          jsdoc2md: {
              oneOutputFile: {
                  src: 'lib/*.js',
                  dest: 'doc/api.md'
              }
          },
          concat: {
              options: {
                  separator: '\n'
              },
              dist: {
                  src: ['doc/README.header.md', 'doc/api.md', 'doc/README.footer.md'],
                  dest: 'README.md'
              }
          },
          shell: {
              coveralls: {
                  command: 'node_modules/.bin/nyc node_modules/.bin/mocha tests/*.js && node_modules/.bin/nyc report --reporter=text-lcov | node_modules/.bin/coveralls --force'
              },
              purgebadges: {
                  command: 'nvm exec 6 node_modules/camo-purge/index.js'
              }
          }
      });
  
      grunt.loadNpmTasks('grunt-xo');
      grunt.loadNpmTasks('grunt-simple-mocha');
      grunt.loadNpmTasks('grunt-contrib-concat');
      grunt.loadNpmTasks('grunt-shell');
      grunt.registerTask('test', ['xo', 'shell:coveralls', 'simplemocha', 'shell:purgebadges']);
  
      grunt.loadNpmTasks('grunt-jsdoc-to-markdown');
      grunt.registerTask('doc', ['jsdoc2md', 'concat']);
  };
  
subject: use node 6 for camo-purge