Create the inverse map from unicode to betacode.

    Returns:
    The hash map to convert unicode characters to the beta code representation.

def _create_unicode_map():
    """
    Create the inverse map from unicode to betacode.

    Returns:
    The hash map to convert unicode characters to the beta code representation.
    """
    unicode_map = {}

    for beta, uni in _map.BETACODE_MAP.items():
        # Include decomposed equivalent where necessary.
        norm = unicodedata.normalize('NFC', uni)
        unicode_map[norm] = beta
        unicode_map[uni] = beta

    # Add the final sigmas.
    final_sigma_norm = unicodedata.normalize('NFC', _FINAL_LC_SIGMA)
    unicode_map[final_sigma_norm] = 's'
    unicode_map[_FINAL_LC_SIGMA] = 's'

    return unicode_map