def _extract_gpcrdb_residue_html(txt):
    """
    Extracts the relevant lines for all residues from a GPCRdb html entry.
    
    Parameters
    ----------
        txt : str
            Content (html) of the website with the GPCRdb entry.

    Returns
    -------
        residue_html : list
            A list in which each item contains the html lines for one residue.
            
    """  
    res_start_line = '                        <td class="seqv seqv-sequence">'
    res_end_line = '                        </td>'
    spl = txt.split('\n')
    residue_html = []
    for lnum, line in enumerate(spl):
        if line == res_start_line:
            residue_lines = spl[lnum:lnum+12]
            # Use fewer lines if the residue is shorter
            # (i.e. has no GPCRdb number)
            if residue_lines[-4] == res_end_line:
                residue_lines = residue_lines[:-3]
            residue_html.append(residue_lines)
    return residue_html