from typing import Union


def concat_keypath(*args: Union[str, int]) -> str:
    """Concatenate partial keypaths and keys into a concatenated single
    keypath.

    Args:
        *args (Union[str, int]): The partial keypaths and keys to concatenate.

    Returns:
        str: the concatenated keypath.
    """
    retval = ''
    for arg in args:
        if retval != '':
            retval += '.'
        retval += str(arg)
    return retval