class_docstr: Baseclass for all loaders.  Subclass this and override `get_source` to
  implement a custom loading mechanism.  The environment provides a
  `get_template` method that calls the loader's `load` method to get the
  :class:`Template` object.
  
  A very basic example for a loader that looks up templates on the file
  system could look like this::
  
      from jinja2 import BaseLoader, TemplateNotFound
      from os.path import join, exists, getmtime
  
      class MyLoader(BaseLoader):
  
          def __init__(self, path):
              self.path = path
  
          def get_source(self, environment, template):
              path = join(self.path, template)
              if not exists(path):
                  raise TemplateNotFound(template)
              mtime = getmtime(path)
              with file(path) as f:
                  source = f.read().decode('utf-8')
              return source, path, lambda: mtime == getmtime(path)
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docstr: Iterates over all templates.  If the loader does not support that
  it should raise a :exc:`TypeError` which is the default behavior.
code: def list_templates(self):
      """Iterates over all templates.  If the loader does not support that
      it should raise a :exc:`TypeError` which is the default behavior.
      """
      raise TypeError("this loader cannot iterate over all templates")
  
imports: import os
  import sys
  import weakref
  from hashlib import sha1
  from os import path
  from types import ModuleType
  from ._compat import abc
  from ._compat import fspath
  from ._compat import iteritems
  from ._compat import string_types
  from .exceptions import TemplateNotFound
  from .utils import internalcode
  from .utils import open_if_exists
label_desc: Use image node_id 2 for calling the BaseLoader obj's underlying member method code with example usage: obj.list_templates() without return types