Typing directives

7 python typing-spec rules tagged directives.

• directives_assert_type Invalid assert_type() call
• directives_assert_type_2 assert_type() type mismatch
• directives_cast Invalid cast() call
• directives_deprecated Use of deprecated class, function, or method
• directives_disjoint_base PEP 800 disjoint bases
• directives_reveal_type Invalid reveal_type() call
• directives_version_platform Variable defined only in dead version/platform branch