Write a function that creates a hash with each (key, value) pair being the (lower case, upper case) versions of a letter, respectively.

Examples

mapping(["p", "s"]) ➞ { "p" => "P", "s" => "S" }

mapping(["a", "b", "c"]) ➞ { "a" => "A", "b" => "B", "c" => "C" }

mapping(["a", "v", "y", "z"]) ➞ { "a" => "A", "v" => "V", "y" => "Y", "z" => "Z" }

Notes

All of the letters in the input list will always be lowercase.