def get_default_query_ids(source_id, model):
    """
    Returns set of Strings, representing source_id's default queries

    Keyword Parameters:
    source_id  -- String, representing API ID of the selection source
    model  -- Dict, representing current DWSupport configuration

    >>> from copy import deepcopy
    >>> no_query_model = { 'queries': []
    ...                   ,'associations': []
    ...                   ,'tables': [{'name': 'foo_fact', 'type': 'fact'}]
    ...                   ,'variables': [ { 'table': 'foo_fact'
    ...                                    ,'column': 'foo_ml'}]
    ...                   ,'variable_custom_identifiers': []}
    >>> source = 'my_example.foo_fact'
    >>> # Check unspecified 'defaults' on a source without 'queries'
    >>> empty_defaults = []
    >>> get_default_query_ids(source, no_query_model)
    set()
    >>> # Check a source with a 'query'
    >>> test_model = { 'queries': [{ 'table': 'foo_fact', 'name': 'core'
    ...                             ,'variables': {'foo_fact': ['foo_ml']}
    ...                            }]
    ...               ,'associations': []
    ...               ,'tables': [{'name': 'foo_fact', 'type': 'fact'}]
    ...               ,'variables': [ { 'table': 'foo_fact'
    ...                                ,'column': 'foo_ml'}
    ...                              ,{ 'table': 'foo_fact'
    ...                                ,'column': 'foo_operation_code'}]
    ...               ,'variable_custom_identifiers': []}
    >>> get_default_query_ids(source, test_model)
    {'core'}
    >>> # Check a source with multiple 'queries'
    >>> multiple_query_model = deepcopy(test_model)
    >>> multiple_query_model['queries'].append({
    ...     'table': 'foo_fact'
    ...     ,'name': 'everything'
    ...     ,'variables': {
    ...          'foo_fact': [
    ...              'foo_ml'
    ...             ,'foo_operation_code']}
    ... })
    >>> defaults_output = get_default_query_ids(source, multiple_query_model)
    >>> defaults_output == {'core', 'everything'}
    True
    """
    defaults = set()
    source_project, source_table_name = source_id.split('.')

    for query in model['queries']:
        if query['table'] == source_table_name: #add it
            set_of_one_identifier_name_to_add = {query['name']}
            defaults.update(set_of_one_identifier_name_to_add)
    return defaults