code: def isin(self, values):
          
          result = algorithms.isin(self, values)
          return self._constructor(result, index=self.index).__finalize__(self)
docs: Check whether `values` are contained in Series.
  
          Return a boolean Series showing whether each element in the Series
          matches an element in the passed sequence of `values` exactly.
  
          Parameters
          ----------
          values : set or list-like
              The sequence of values to test. Passing in a single string will
              raise a ``TypeError``. Instead, turn a single string into a
              list of one element.
  
              .. versionadded:: 0.18.1
  
                Support for values as a set.
  
          Returns
          -------
          Series
              Series of booleans indicating if each element is in values.
  
          Raises
          ------
          TypeError
            * If `values` is a string
  
          See Also
          --------
          DataFrame.isin : Equivalent method on DataFrame.
  
          Examples
          --------
          >>> s = pd.Series(['lama', 'cow', 'lama', 'beetle', 'lama',
          ...                'hippo'], name='animal')
          >>> s.isin(['cow', 'lama'])
          0     True
          1     True
          2     True
          3    False
          4     True
          5    False
          Name: animal, dtype: bool
  
          Passing a single string as ``s.isin('lama')`` will raise an error. Use
          a list of one element instead:
  
          >>> s.isin(['lama'])
          0     True
          1    False
          2     True
          3    False
          4     True
          5    False
          Name: animal, dtype: bool