#!/usr/bin/env python

__all__ = []

try:
    from silk.webdoc import css, html, node
    __all__.extend(('css', 'html', 'node'))
except ImportError:
    pass

try:
    from silk.webdb import (
        AuthenticationError, BoolColumn, Column, DB, DataColumn,
        DateTimeColumn, FloatColumn, IntColumn, RecordError, ReferenceColumn,
        RowidColumn, SQLSyntaxError, StrColumn, Table, UnknownDriver, connect
    )
    __all__.extend((
        'AuthenticationError', 'BoolColumn', 'Column', 'DB', 'DataColumn',
        'DateTimeColumn', 'FloatColumn', 'IntColumn', 'RecordError',
        'ReferenceColumn', 'RowidColumn', 'SQLSyntaxError', 'StrColumn',
        'Table', 'UnknownDriver', 'connect'
    ))
except ImportError:
    pass

try:
    from silk.webreq import (
        B64Document, BaseRouter, Document, FormData, HTTP, Header, HeaderList,
        PathRouter, Query, Redirect, Response, TextView, URI
    )

    __all__.extend((
        'B64Document', 'BaseRouter', 'Document', 'FormData', 'HTTP', 'Header',
        'HeaderList', 'PathRouter', 'Query', 'Redirect', 'Response',
        'TextView', 'URI'
    ))
except ImportError:
    pass

#!/usr/bin/env python

__all__ = []

try:
    from silk.webdoc import css, html, node
    __all__ += ['css', 'html', 'node']
except ImportError:
    pass

try:
    from silk.webdb import (
        AuthenticationError, BoolColumn, Column, DB, DataColumn,
        DateTimeColumn, FloatColumn, IntColumn, RecordError, ReferenceColumn,
        RowidColumn, SQLSyntaxError, StrColumn, Table, UnknownDriver, connect
    )
    __all__ += [
        'AuthenticationError', 'BoolColumn', 'Column', 'DB', 'DataColumn',
        'DateTimeColumn', 'FloatColumn', 'IntColumn', 'RecordError',
        'ReferenceColumn', 'RowidColumn', 'SQLSyntaxError', 'StrColumn',
        'Table', 'UnknownDriver', 'connect'
    ]
except ImportError:
    pass

try:
    from silk.webreq import (
        B64Document, BaseRouter, Document, FormData, HTTP, Header, HeaderList,
        PathRouter, Query, Redirect, Response, TextView, URI
    )

    __all__ += [
        'B64Document', 'BaseRouter', 'Document', 'FormData', 'HTTP', 'Header',
        'HeaderList', 'PathRouter', 'Query', 'Redirect', 'Response',
        'TextView', 'URI'
    ]
except ImportError:
    pass

Use += to modify __all__, to appease flake8
Use += to modify __all__, to appease flake8
