from typing import Iterable


def _unique(*args: Iterable) -> list:
    """Return a list of all unique values, in order of first appearance.

    Args:
        args: Iterables of values.

    Examples:
        >>> _unique([0, 2], (2, 1))
        [0, 2, 1]
        >>> _unique([{'x': 0, 'y': 1}, {'y': 1, 'x': 0}], [{'z': 2}])
        [{'x': 0, 'y': 1}, {'z': 2}]
    """
    values = []
    for parent in args:
        for child in parent:
            if child not in values:
                values.append(child)
    return values