'Return the source of the current line of this frame.  You
probably want to .strip() it as well, as it is likely to have
leading whitespace.
If context is given, then that many lines on either side will
also be returned.  E.g., context=1 will give 3 lines.'

def get_source_line(self, context=0):

    if ((not self.filename) or (not self.lineno)):
        return None
    lines = []
    for lineno in range((self.lineno - context), ((self.lineno + context) + 1)):
        lines.append(linecache.getline(self.filename, lineno))
    return ''.join(lines)
