<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def getnames():
 """ get mail names """

    namestring = ""
    addmore = 1
    while addmore:
        scientist = input("Enter  name  - <Return> when done ")
        if scientist != "":
            namestring = namestring + ":" + scientist
        else:
            namestring = namestring[1:]
            addmore = 0
    return namestring