the_worst_way.py

"""
In [1]: from the_worst_way import why_though

In [2]: import ast

In [3]: code = '''
   ...: if a == 1 and a == 2 and a == 3:
   ...:     print('ayy')
   ...: else:
   ...:     print('lmao')
   ...: '''

In [4]: exec(compile(why_though.visit(ast.parse(code)), '<string>', 'exec'))
ayy
"""

import ast


@object.__new__
class why_though(ast.NodeTransformer):
    @staticmethod
    def _matches(node):
        if not isinstance(node.op, ast.And):
            return False

        try:
            a, b, c = node.values
        except ValueError:
            return False

        for n, subnode in enumerate(node.values, 1):
            if not (isinstance(subnode, ast.Compare) and
                    isinstance(subnode.left, ast.Name) and
                    subnode.left.id == 'a' and
                    len(subnode.ops) == 1 and
                    isinstance(subnode.ops[0], ast.Eq) and
                    len(subnode.comparators) == 1 and
                    isinstance(subnode.comparators[0], ast.Num) and
                    subnode.comparators[0].n == n):
                return False

        return True

    def visit_BoolOp(self, node):
        return (
            ast.copy_location(ast.NameConstant(value=True), node)
            if self._matches(node) else
            node
        )