The get_alias function is set by a few different things:
            - if there is a 'generate_alias_name' macro in the root project,
                it will be used.
            - if that does not exist but there is a 'generate_alias_name'
                macro in the 'dbt' internal project, that will be used
            - if neither of those exist (unit tests?), a function that returns
                the 'default alias' as set in the model's filename or alias
                configuration.

def get_alias_func(self):
        """The get_alias function is set by a few different things:
            - if there is a 'generate_alias_name' macro in the root project,
                it will be used.
            - if that does not exist but there is a 'generate_alias_name'
                macro in the 'dbt' internal project, that will be used
            - if neither of those exist (unit tests?), a function that returns
                the 'default alias' as set in the model's filename or alias
                configuration.
        """
        if self._get_alias_func is not None:
            return self._get_alias_func

        get_alias_macro = self.macro_manifest.find_macro_by_name(
            'generate_alias_name',
            self.root_project_config.project_name
        )
        if get_alias_macro is None:
            get_alias_macro = self.macro_manifest.find_macro_by_name(
                'generate_alias_name',
                GLOBAL_PROJECT_NAME
            )
        if get_alias_macro is None:
            def get_alias(node, custom_alias_name=None):
                if custom_alias_name is None:
                    return node.name
                else:
                    return custom_alias_name
        else:
            root_context = dbt.context.parser.generate_macro(
                get_alias_macro, self.root_project_config,
                self.macro_manifest
            )
            get_alias = get_alias_macro.generator(root_context)

        self._get_alias_func = get_alias
        return self._get_alias_func