code: function isReadableStream (stream) {
    return stream !== null
      && typeof (stream) === 'object'
      && typeof (stream.pipe) === 'function'
      && typeof (stream._read) === 'function'
      && typeof (stream._readableState) === 'object'
      && stream.readable !== false
  }
docs: Returns a boolean indication if stream param
  is a readable stream or not.
  
  @param {*} stream
  
  @return {Boolean}