Stop SQLAlchemy warnings about registering 'flatten' twice

src/snowflake/sqlalchemy/__init__.py

@@ -61,6 +61,7 @@
     VARBINARY,
     VARIANT,
 )
+from .functions import flatten as flatten
 from .util import _url as URL
 
 base.dialect = dialect = snowdialect.dialect

src/snowflake/sqlalchemy/base.py

@@ -13,14 +13,13 @@
 from sqlalchemy.orm import context
 from sqlalchemy.orm.context import _MapperEntity
 from sqlalchemy.schema import Sequence, Table
-from sqlalchemy.sql import compiler, expression, functions
+from sqlalchemy.sql import compiler, expression
 from sqlalchemy.sql.base import CompileState
 from sqlalchemy.sql.elements import quoted_name
 from sqlalchemy.sql.selectable import Lateral, SelectState
 
 from .compat import IS_VERSION_20, args_reducer, string_types
 from .custom_commands import AWSBucket, AzureContainer, ExternalStage
-from .functions import flatten
 from .util import (
     _find_left_clause_to_join_from,
     _set_connection_interpolate_empty_sequences,
@@ -1064,5 +1063,3 @@ def visit_GEOMETRY(self, type_, **kw):
 
 
 construct_arguments = [(Table, {"clusterby": None})]
-
-functions.register_function("flatten", flatten)