<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def last_two_lines_blank(source):
 """Are the two last lines blank, and not the third last one?"""

    if len(source) < 3:
        return False
    return not _BLANK_LINE.match(source[-3]) and _BLANK_LINE.match(source[-2]) and _BLANK_LINE.match(source[-1])