For this next exercise, you'll need to complete the function gen_pattern, which, when called with a string of length 1, will generate an ASCII art pattern of concentric diamonds using those characters. The following are examples of patterns returned by the function:

gen_pattern('XY') ..Y.. Y.X.Y ..Y.. 

> gen_pattern('WXYZ') ......Z...... ....Z.Y.Z.... ..Z.Y.X.Y.Z.. Z.Y.X.W.X.Y.Z ..Z.Y.X.Y.Z.. ....Z.Y.Z.... ......Z...... 

please make all indentations clear in the solution code