text: const crypto = require('crypto');
  const each = require('./each');
  
  const hash = (sequence, options) => {
      const settings = Object.assign({
          algorithm: 'sha1', // 'sha1', 'md5', 'sha256', 'sha512'
          encoding: 'hex' // 'hex', 'base64'
      }, options);
  
      const shasum = crypto.createHash(settings.algorithm);
      shasum.update(sequence);
      return shasum.digest(settings.encoding);
  };
  
  const action = options => {
      return each(obj => {
          obj.hash = hash(obj.content, options);
      }, {filter: obj => obj && (obj.content || obj.content === '')});
  };
  
  action.string = hash;
  module.exports = action;
  