code: def _validate_buckets(categorical, k, scheme):
      
      if categorical and (k != 5 or scheme):
          raise ValueError("Invalid input: categorical cannot be specified as True simultaneously with scheme or k "
                           "parameters")
      if k > 10:
          warnings.warn("Generating a choropleth using a categorical column with over 10 individual categories. "
                        "This is not recommended!")
      if not scheme:
          scheme = 'Quantiles'  # This trips it correctly later.
      return categorical, k, scheme
docs: This method validates that the hue parameter is correctly specified. Valid inputs are:
  
          1. Both k and scheme are specified. In that case the user wants us to handle binning the data into k buckets
             ourselves, using the stated algorithm. We issue a warning if the specified k is greater than 10.
          2. k is left unspecified and scheme is specified. In that case the user wants us to handle binning the data
             into some default (k=5) number of buckets, using the stated algorithm.
          3. Both k and scheme are left unspecified. In that case the user wants us bucket the data variable using some
             default algorithm (Quantiles) into some default number of buckets (5).
          4. k is specified, but scheme is not. We choose to interpret this as meaning that the user wants us to handle
             bucketing the data into k buckets using the default (Quantiles) bucketing algorithm.
          5. categorical is True, and both k and scheme are False or left unspecified. In that case we do categorical.
          Invalid inputs are:
          6. categorical is True, and one of k or scheme are also specified. In this case we raise a ValueError as this
             input makes no sense.
  
      Parameters
      ----------
      categorical : boolean
          Whether or not the data values given in ``hue`` are already a categorical variable.
  
      k : int
          The number of categories to use. This variable has no effect if ``categorical`` is True, and will be set to 5
          by default if it is False and not already given.
  
      scheme : str
          The mapclassify scheme that the variable will be categorized according to (or rather, a string representation
          thereof).
  
      Returns
      -------
      (categorical, k, scheme) : tuple
          A possibly modified input tuple meant for reassignment in place.