Graphql-compiler

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- Add a new :code:`filter` operator: :code:`has_edge_degree`.
`52 <https://github.com/kensho-technologies/graphql-compiler/pull/52>`__
- Lots of under-the-hood cleanup and improvements.

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- Add workaround for `OrientDB type inconsistency when filtering
lists <https://github.com/orientechnologies/orientdb/issues/7811>`__
`42 <https://github.com/kensho-technologies/graphql-compiler/pull/42>`__

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- **BREAKING**: Requires OrientDB 2.2.28+, since it depends on two
OrientDB bugs being fixed: `bug
1 <https://github.com/orientechnologies/orientdb/issues/7225>`__ `bug
2 <https://github.com/orientechnologies/orientdb/issues/7754>`__
- Allow type coercions and filtering within :code:`fold` scopes.
- Fix bug where :code:`filter` directives could end up ignored if more
than two were in the same scope
- Optimize type coercions in :code:`optional` and :code:`recurse` scopes.
- Optimize multiple outputs from the same :code:`fold` scope.
- Allow having multiple :code:`filter` directives on the same field
`33 <https://github.com/kensho-technologies/graphql-compiler/pull/33>`__
- Allow using the :code:`name_or_alias` filtering operation on interface
types
`37 <https://github.com/kensho-technologies/graphql-compiler/pull/37>`__

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- Add support for Python 3
`31 <https://github.com/kensho-technologies/graphql-compiler/pull/31>`__
- Make it possible to use :code:`fold` together with union-typed vertex
fields
`32 <https://github.com/kensho-technologies/graphql-compiler/pull/32>`__

Thanks to :code:`ColCarroll` for making the compiler support Python 3!

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- Fix a minor bug in the GraphQL pretty-printer
`30 <https://github.com/kensho-technologies/graphql-compiler/pull/30>`__

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- Make the :code:`graphql_to_ir()` easier to use by making it automatically
add a new line to the end of the GraphQL query string. Works around
an issue in the :code:`graphql-core`\ dependency library:
`https://github.com/graphql-python/graphql-core/issues/98 <https://github.com/graphql-python/graphql-core/issues/98>`__
- Robustness improvements for the pretty-printer
`27 <https://github.com/kensho-technologies/graphql-compiler/pull/27>`__

Thanks to :code:`benlongo` for their contributions.