def find(cls, where='.', exclude=(), include=('*', )):
        """Return a list all Python packages found within directory 'where'

        'where' should be supplied as a "cross-platform" (i.e. URL-style)
        path; it will be converted to the appropriate local path syntax.
        'exclude' is a sequence of package names to exclude; '*' can be used
        as a wildcard in the names, such that 'foo.*' will exclude all
        subpackages of 'foo' (but not 'foo' itself).

        'include' is a sequence of package names to include.  If it's
        specified, only the named packages will be included.  If it's not
        specified, all found packages will be included.  'include' can contain
        shell style wildcard patterns just like 'exclude'.

        The list of included packages is built up first and then any
        explicitly excluded packages are removed from it.
        """
        out = cls._find_packages_iter(convert_path(where))
        out = cls.require_parents(out)
        includes = cls._build_filter(*include)
        excludes = cls._build_filter('ez_setup', '*__pycache__', *exclude)
        out = filter(includes, out)
        out = filterfalse(excludes, out)
        return list(out)
Return a list all Python packages found within directory 'where'

        'where' should be supplied as a "cross-platform" (i.e. URL-style)
        path; it will be converted to the appropriate local path syntax.
        'exclude' is a sequence of package names to exclude; '*' can be used
        as a wildcard in the names, such that 'foo.*' will exclude all
        subpackages of 'foo' (but not 'foo' itself).

        'include' is a sequence of package names to include.  If it's
        specified, only the named packages will be included.  If it's not
        specified, all found packages will be included.  'include' can contain
        shell style wildcard patterns just like 'exclude'.

        The list of included packages is built up first and then any
        explicitly excluded packages are removed from it.
        
bin/pip.py