code: def astype(self, dtype, copy=True):
          
          return np.array(self, dtype=dtype, copy=copy)
docs: Cast to a NumPy array with 'dtype'.
  
          Parameters
          ----------
          dtype : str or dtype
              Typecode or data-type to which the array is cast.
          copy : bool, default True
              Whether to copy the data, even if not necessary. If False,
              a copy is made only if the old dtype does not match the
              new dtype.
  
          Returns
          -------
          array : ndarray
              NumPy ndarray with 'dtype' for its dtype.