def dict_valkey(diction, val):
    """
    Given passed dictionary reference, returns the first key found whose value is equal to val, 
    or None if no matching value.

    :param diction: the dictionary whose key is to be looked for 
    :type diction: reference to dictionary object
    :param val: reference to dictionary
    :returns: Reference to the dictionary's matching key object
    """
    for dkey, dval in diction.iteritems():
        if dval == val:
            return dkey
    return None