code: def heatmap(n_x=5, n_y=10):
      """
      Returns a DataFrame with the required format for
      a heatmap plot
  
      Parameters:
      -----------
              n_x : int
                      Number of x categories
              n_y : int
                      Number of y categories
      """
      x = ["x_" + str(_) for _ in range(n_x)]
      y = ["y_" + str(_) for _ in range(n_y)]
      return pd.DataFrame(
          surface(n_x - 1, n_y - 1).values, index=x, columns=y
      )
  
imports: import os
  import string
  import numpy
  import pandas
  from .auth import get_config_file
  from .exceptions import CufflinksError
label_desc: Use image node_id 8 for calling a global function with example usage: heatmap(n_x, n_y) and returns: pd