def token_to_char_offset(e, candidate_idx, token_idx):
    """Converts a token index to the char offset within the candidate."""
    c = e["long_answer_candidates"][candidate_idx]
    char_offset = 0
    for i in range(c["start_token"], token_idx):
        t = e["document_tokens"][i]
        if not t["html_token"]:
            token = t["token"].replace(" ", "")
            char_offset += len(token) + 1 # + 1 is for the space
    return char_offset