------------------ - Downgrade attrs from >16 (17.x) to ~=16.3 to fix version conflict error
1.6.0
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- Constant now takes multiple possible options and accepts any of them - Added a UnicodeDecimal type that validates decimals transported as unicode strings.
1.5.0
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- Added BooleanValidator field - Fixed behaviour when subclassing Dictionary to provide attributes in class body
1.4.0
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- Added Latitude and Longitude fields - Added IPv4Address, IPv6Address, and IPAddress fields - Added Any and All combinatorial fields - Dictionary can now be subclassed, `contents` and `optional_keys` may be provided in the class body.
1.3.1
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- Error class now uses attrs rather than custom reimplementation
1.3.0
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- Add validation and description funcionality to fields for introspection - Now compatible with Python 3