code: function( input ) {
  
  		if ( input == null ) {
  
  			input = this.result;
  
  		}
  
  		for (var i = 0; i < input.length; i++) {
  
  			this.result += this.persian_number[ parseInt( input.charAt( i ) ) ];
  
      }
  
  		return this;
  
  	}
docs: *******************************************************************
  Convert english number to persian number
  *********************************************************************
  @since 25 Jun 2015
  @var input string
  @return object