class_docstr: An OrderedSet is a custom MutableSet that remembers its order, so that
  every entry has an index that can be looked up.
  
  Example:
      >>> OrderedSet([1, 1, 2, 3, 2])
      OrderedSet([1, 2, 3])
class_docstr_tok: ["An","OrderedSet","is","a","custom","MutableSet","that","remembers","its","order",",","so","that","every","entry","has","an","index","that","can","be","looked","up",".","Example",":",">",">",">","OrderedSet","(","[","1",",","1",",","2",",","3",",","2","]",")","OrderedSet","(","[","1",",","2",",","3","]",")"]
docstr: Returns the number of unique elements in the ordered set
  
  Example:
      >>> len(OrderedSet([]))
      0
      >>> len(OrderedSet([1, 2]))
      2
docstr_tok: ["Returns","the","number","of","unique","elements","in","the","ordered","set","Example",":",">",">",">","len","(","OrderedSet","(","[","]",")",")","0",">",">",">","len","(","OrderedSet","(","[","1",",","2","]",")",")","2"]
code: def __len__(self):
      """
      Returns the number of unique elements in the ordered set
  
      Example:
          >>> len(OrderedSet([]))
          0
          >>> len(OrderedSet([1, 2]))
          2
      """
      return len(self.items)
  
imports: import itertools
  from collections import deque
label_desc: Use image node_id 2 for calling the OrderedSet obj's underlying member method code with example usage: obj.__len__() and returns: len