Generalize Collection Type Lookup

[JSAbrahams]

Summary

Generalize how one looks at a type:

• Look at whether it defines __iter__, which then returns the iterator type.
• We lookup the class in the Context.
• We look at whether it defines __next__, as any proper iterator class should.
• We return the return type of this __next__ function.

This solution means that the collection lookup generalizes to all types which define an iterator. For instance, we can now also index Strings, which also have an iterator.

Also final round of tests before the next release. Shouldn't be too much since we typically test as features are implemented, but looking at it with a fresh perspective can't hurt though.

Added Tests

• Add extra test to verify that all in union must implement a method, in this case bool.
• All range and slice options as return of a function.
• Iterate over union of different types which are both iterable.
• Sad iterate over union of different types which are both iterable, but one of which does not implement method needed in loop body (minus op),
• Access types (in definition), which used to be accessed improperly
• E-numbers, which was already working but just an extra check
• Re-add match test, which tests match statements and also matching identifiers

[codecov[bot]]

Codecov Report

:exclamation: No coverage uploaded for pull request base (develop@9dd3502). Click here to learn what that means. The diff coverage is n/a.

@@            Coverage Diff             @@
##             develop     #281   +/-   ##
==========================================
  Coverage           ?   85.43%           
==========================================
  Files              ?       99           
  Lines              ?     9811           
  Branches           ?        0           
==========================================
  Hits               ?     8382           
  Misses             ?     1429           
  Partials           ?        0           

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[JSAbrahams]

Well, if we're so close to 84% coverage, maybe sneak in a few extra tests here.

[JSAbrahams]

Re-added all ignored tests which previously failed, quite a lot of bugs and/or missing language features which had been solved in the meantime.