How to use the birdseye.tracer.TreeTracerBase function in birdseye

def test_async_forbidden(self):
        from birdseye.tracer import TreeTracerBase
        tracer = TreeTracerBase()
        with self.assertRaises(ValueError):
            exec("""
@tracer
async def f(): pass""")

        if sys.version_info >= (3, 6):
            with self.assertRaises(ValueError):
                exec("""
@tracer

class Series(object):
        pass

try:
    from django.db.models import QuerySet
except ImportError:
    class QuerySet(object):
        pass

warn_if_outdated('birdseye', __version__)

CodeInfo = namedtuple('CodeInfo', 'db_func traced_file arg_names')


class BirdsEye(TreeTracerBase):
    """
    Decorate functions with an instance of this class to debug them,
    or just use the existing instance `eye`.
    """

    def __init__(self, db_uri=None, num_samples=None):
        """
        Set db_uri to specify where the database lives, as an alternative to
        the environment variable BIRDSEYE_DB.
        """
        super(BirdsEye, self).__init__()
        self._db_uri = db_uri
        self._code_infos = {}  # type: Dict[CodeType, CodeInfo]
        self._last_call_id = None
        self._ipython_cell_value = None
        self.num_samples = num_samples or dict(

def visit_expr(self, node):
        # type: (ast.expr) -> ast.Call
        """
        each expression e gets wrapped like this:
            _treetrace_hidden_after_expr(_treetrace_hidden_before_expr(_tree_index), e)

        where the _treetrace_* functions are the corresponding methods with the
        TreeTracerBase and traced_file arguments already filled in (see _trace_methods_dict)
        """

        before_marker = self._create_simple_marker_call(node, TreeTracerBase._treetrace_hidden_before_expr)
        ast.copy_location(before_marker, node)

        after_marker = ast.Call(
            func=ast.Name(id=TreeTracerBase._treetrace_hidden_after_expr.__name__,
                          ctx=ast.Load()),
            args=[
                before_marker,
                super(_NodeVisitor, self).generic_visit(node),
            ],
            keywords=[],
        )
        ast.copy_location(after_marker, node)
        ast.fix_missing_locations(after_marker)

        return after_marker

def visit_expr(self, node):
        # type: (ast.expr) -> ast.Call
        """
        each expression e gets wrapped like this:
            _treetrace_hidden_after_expr(_treetrace_hidden_before_expr(_tree_index), e)

        where the _treetrace_* functions are the corresponding methods with the
        TreeTracerBase and traced_file arguments already filled in (see _trace_methods_dict)
        """

        before_marker = self._create_simple_marker_call(node, TreeTracerBase._treetrace_hidden_before_expr)
        ast.copy_location(before_marker, node)

        after_marker = ast.Call(
            func=ast.Name(id=TreeTracerBase._treetrace_hidden_after_expr.__name__,
                          ctx=ast.Load()),
            args=[
                before_marker,
                super(_NodeVisitor, self).generic_visit(node),
            ],
            keywords=[],
        )
        ast.copy_location(after_marker, node)
        ast.fix_missing_locations(after_marker)

        return after_marker

def visit_stmt(self, node):
        # type: (ast.stmt) -> ast.With
        """
        Every statement in the original code becomes:

        with _treetrace_hidden_with_stmt(_tree_index):
            

        where the _treetrace_hidden_with_stmt function is the the corresponding method with the
        TreeTracerBase and traced_file arguments already filled in (see _trace_methods_dict)
        """
        context_expr = self._create_simple_marker_call(
            super(_NodeVisitor, self).generic_visit(node),
            TreeTracerBase._treetrace_hidden_with_stmt)

        if PY3:
            wrapped = ast.With(
                items=[ast.withitem(context_expr=context_expr)],
                body=[node],
            )
        else:
            wrapped = ast.With(
                context_expr=context_expr,
                body=[node],
            )
        ast.copy_location(wrapped, node)
        ast.fix_missing_locations(wrapped)
        return wrapped

class Series(object):
        pass

try:
    from django.db.models import QuerySet
except ImportError:
    class QuerySet(object):
        pass


warn_if_outdated('birdseye', __version__)

CodeInfo = namedtuple('CodeInfo', 'db_func traced_file arg_names')


class BirdsEye(TreeTracerBase):
    """
    Decorate functions with an instance of this class to debug them,
    or just use the existing instance `eye`.
    """

    def __init__(self, db_uri=None, num_samples=None):
        """
        Set db_uri to specify where the database lives, as an alternative to
        the environment variable BIRDSEYE_DB.
        """
        super(BirdsEye, self).__init__()
        self._db_uri = db_uri
        self._code_infos = {}  # type: Dict[CodeType, CodeInfo]
        self._last_call_id = None
        self._ipython_cell_value = None
        self.num_samples = num_samples or dict(