def mod_relpath(target_modpath: str, base_modpath: str) ->str:
    """ get relative path to `target_modpath` from `base_modpath`

    i.g.
        Args:
            `target_modpath`: nayvy.importing.import_statement
            `base_modpath`: nayvy.projects.path
        Returns:
            ..importing.import_statement
    """
    if target_modpath == base_modpath:
        return '.'
    target_path_elms = target_modpath.split('.')
    base_path_elms = base_modpath.split('.')
    if target_path_elms[0] != base_path_elms[0]:
        return target_modpath
    common_elm_num = 0
    for target_elm, base_elm in zip(target_path_elms, base_path_elms):
        if target_elm != base_elm:
            break
        common_elm_num += 1
    return '.' * (len(base_path_elms) - common_elm_num) + '.'.join(
        target_path_elms[common_elm_num:])
