'Return the line number at which table data begins.'

def start_line(self, lines):

    for (i, line) in enumerate(lines):
        if (not isinstance(line, SoupString)):
            raise TypeError('HTML    lines    should    be    of    type    SoupString')
        soup = line.soup
        if (soup.td is not None):
            if (soup.th is not None):
                raise core.InconsistentTableError('HTML    tables    cannot    have    headings    and    data    in    the    same    row')
            return i
    raise core.InconsistentTableError('No    start    line    found    for    HTML    data')
