Function tolong()

What's wrong with the following that I keep getting the error message below?

temp_list=List();

for each selection in Team_Members

{

e = Team_Members[ID == selection.tolong()].Email_ID;

temp_list.add(e);

}

Team_Members_Text_List=temp_list.tostring();

Error at line number : 4
Not able to find 'tolong' function