How to use the pgcli.packages.sqlcompletion.Datatype function in pgcli

def test_alter_column_type_suggests_types():
    q = "ALTER TABLE foo ALTER COLUMN bar TYPE "
    assert set(suggest_type(q, q)) == set(
        [Datatype(schema=None), Table(schema=None), Schema()]
    )

def test_cast_operator_suggests_schema_qualified_types(text):
    assert set(suggest_type(text, text)) == set(
        [Datatype(schema="bar"), Table(schema="bar")]
    )

def test_cast_operator_suggests_types(text):
    assert set(suggest_type(text, text)) == set(
        [Datatype(schema=None), Table(schema=None), Schema()]
    )

def test_identifier_suggests_types_in_parentheses(text):
    assert set(suggest_type(text, text)) == set(
        [Datatype(schema=None), Table(schema=None), Schema()]
    )

def test_dT_suggests_schema_or_datatypes():
    text = "\\dT "
    suggestions = suggest_type(text, text)
    assert set(suggestions) == set([Schema(), Datatype(schema=None)])

def test_schema_qualified_dT_suggests_datatypes():
    text = "\\dT foo."
    suggestions = suggest_type(text, text)
    assert suggestions == (Datatype(schema="foo"),)

suggestion_matchers = {
        FromClauseItem: get_from_clause_item_matches,
        JoinCondition: get_join_condition_matches,
        Join: get_join_matches,
        Column: get_column_matches,
        Function: get_function_matches,
        Schema: get_schema_matches,
        Table: get_table_matches,
        TableFormat: get_table_formats,
        View: get_view_matches,
        Alias: get_alias_matches,
        Database: get_database_matches,
        Keyword: get_keyword_matches,
        Special: get_special_matches,
        Datatype: get_datatype_matches,
        NamedQuery: get_namedquery_matches,
        Path: get_path_matches,
    }

    def populate_scoped_cols(self, scoped_tbls, local_tbls=()):
        """Find all columns in a set of scoped_tables.

        :param scoped_tbls: list of TableReference namedtuples
        :param local_tbls: tuple(TableMetadata)
        :return: {TableReference:{colname:ColumnMetaData}}

        """
        ctes = dict((normalize_ref(t.name), t.columns) for t in local_tbls)
        columns = OrderedDict()
        meta = self.dbmetadata