Without arguments, return the list of names in the current local scope. With an argument, attempt to return a list of valid attributes for that object.
dir()>>> import struct
>>> dir() show the names in the module namespace
['__builtins__', '__name__', 'struct']
>>> dir(struct) show the names in the struct module
['Struct', '__all__', '__builtins__', '__cached__', '__doc__', '__file__',
'__initializing__', '__loader__', '__name__', '__package__',
'_clearcache', 'calcsize', 'error', 'pack', 'pack_into',
'unpack', 'unpack_from']
>>> class Shape:
... def __dir__(self):
... return ['area', 'perimeter', 'location']
>>> s = Shape()
>>> dir(s)
['area', 'location', 'perimeter']