Creating a Picture Frame

Create a function that takes the width, height and character and returns a picture frame as a 2D list.

Examples

get_frame(4, 5, "#") ➞ [
  ["####"],
  ["#  #"],
  ["#  #"],
  ["#  #"],
  ["####"]
]
# Frame is 4 characters wide and 5 characters tall.

get_frame(10, 3, "*") ➞ [
  ["**********"],
  ["*        *"],
  ["**********"]
]
# Frame is 10 characters and wide and 3 characters tall.

get_frame(2, 5, "0") ➞ "invalid"
# Frame's width is not more than 2.

Notes

• Remember the gap.
• Return "invalid" if width or height is 2 or less (can't put anything inside).