import string

def convert_line_endings(temp, mode):
        #modes:  0 - Unix, 1 - Mac, 2 - DOS
        if mode == 0:
                temp = string.replace(temp, '\r\n', '\n')
                temp = string.replace(temp, '\r', '\n')
        elif mode == 1:
                temp = string.replace(temp, '\r\n', '\r')
                temp = string.replace(temp, '\n', '\r')
        elif mode == 2:
                import re
                temp = re.sub("\r(?!\n)|(?<!\r)\n", "\r\n", temp)
        return temp