Consider an image that is composed of a number of colored small squares, each colored in one of these 8 colors: red, green, blue, cyan, magenta, yellow, black, white. The colors are stored in a String using the first letter of each color (R, G, B, C, M, Y, K, W). Each row in the image is terminated by a newline character ('\n'). Here is an example of an image:

String imageCode = "RRR\nRGR\nRRR\n";

This is a green square surrounded by red squares.

Your task is to write a method that doubles the image in size, making each square twice as large in each direction. For example, when calling doubleImage with imageCode, the returned image is

"RRRRRR\nRRRRRR\nRRGGRR\nRRGGRR\nRRRRRR\nRRRRRR\n"