lib/resources/messages.js
function(conversationId, userId, text, callback) {
      send(null, conversationId, utils.messageText('user_id', userId, text), callback);
    }
function(conversationId, userId, text, callback) {
      send(null, conversationId, utils.messageText('user_id', userId, text), callback);
    }
function ( conversationId , userId , text , callback ) { send ( null , conversationId , utils . messageText ( 'user_id' , userId , text ) , callback ) ; }
Send a plain text message from `userId`

@param  {String}   conversationId Conversation ID
@param  {String}   userId         User ID
@param  {String}   text           Message text
@param  {Function} callback       Callback function
Send a plain text message from userId