Remove duplicates from a list of dictionaries preserving the order.

    We can't use the generic list helper because a dictionary isn't hashable.
    Adapted from http://stackoverflow.com/a/9427216/374865.

def dedupe_list_of_dicts(ld):
    """Remove duplicates from a list of dictionaries preserving the order.

    We can't use the generic list helper because a dictionary isn't hashable.
    Adapted from http://stackoverflow.com/a/9427216/374865.
    """
    def _freeze(o):
        """Recursively freezes a dict into an hashable object.

        Adapted from http://stackoverflow.com/a/21614155/374865.
        """
        if isinstance(o, dict):
            return frozenset((k, _freeze(v)) for k, v in six.iteritems(o))
        elif isinstance(o, (list, tuple)):
            return tuple(_freeze(v) for v in o)
        else:
            return o

    result = []
    seen = set()

    for d in ld:
        f = _freeze(d)
        if f not in seen:
            result.append(d)
            seen.add(f)

    return result