def subdict_in_dict(subdict, superdict):
    """True is subdict in subdict_in_dict. Else False.

    >>> subdict_in_dict({"k1": "v1"}, {"k1": "v1"})
    True
    >>> subdict_in_dict({"k1": "v1"}, {"k1": "v1", "k2": "v2"})
    True
    >>> subdict_in_dict({}, {"k1": "v1"})
    True
    >>> subdict_in_dict({"k1": "v1"}, {})
    False
    """
    return all(item in superdict.items()
               for item in subdict.items())