code: def surface(n_x=20, n_y=20):
      """
      Returns a DataFrame with the required format for
      a surface plot
  
      Parameters:
      -----------
              n_x : int
                      Number of points along the X axis
              n_y : int
                      Number of points along the Y axis
      """
      x = [float(np.random.randint(0, 100))]
      for i in range(n_x):
          x.append(
              x[:1][0] + np.random.randn() * np.random.randint(1, 10)
          )
      df = pd.DataFrame(x)
      for i in range(n_y):
          df[i + 1] = df[i].map(
              lambda x: x + np.random.randn() * np.random.randint(1, 10)
          )
      return df
  
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 17 for calling a global function with example usage: surface(n_x, n_y) and returns: df