code: def sinwave(n=4, inc=0.25):
      """
      Returns a DataFrame with the required format for
      a surface (sine wave) plot
  
      Parameters:
      -----------
              n : int
                      Ranges for X and Y axis (-n,n)
              n_y : int
                      Size of increment along the axis
      """
      x = np.arange(-n, n, inc)
      y = np.arange(-n, n, inc)
      X, Y = np.meshgrid(x, y)
      R = np.sqrt(X**2 + Y**2)
      Z = np.sin(R) / (0.5 * R)
      return pd.DataFrame(Z, 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 18 for calling a global function with example usage: sinwave(n, inc) and returns: pd