code: function assertValidBuildType(value, name, description) {
    if ((value != common.DEBUG) && (value != common.RELEASE)) {
      throw new Error('Invalid build type: <' + value + '>, must be ' +
          'closureProBuild.DEBUG or closureProBuild.RELEASE');
    }
  }
docs: Throws an Error if value isn't a valid build type.
  @param {*} value
  @param {string} name The option name.
  @param {string} description Description of the option.