Pull Request or Exercise Instruction Edit

If it is possible, I’d like to make a request to change the method stringify on the Fixnum class inside of the exercise RSPEC Practice 3.

It currently reads:

# Stringify
#
# In this exercise, you will define a method `Fixnum#stringify(base)`,
# which will return a string representing the original integer in a
# different base (up to base 16). **Do not use the built-in
# `#to_s(base)`**.
#
# To refresh your memory, a few common base systems:
#
# |Base 10 (decimal)     |0   |1   |2   |3   |....|9   |10  |11  |12  |13  |14  |15  |
# |----------------------|----|----|----|----|----|----|----|----|----|----|----|----|
# |Base 2 (binary)       |0   |1   |10  |11  |....|1001|1010|1011|1100|1101|1110|1111|
# |Base 16 (hexadecimal) |0   |1   |2   |3   |....|9   |A   |B   |C   |D   |E   |F   |
#
# Examples of strings your method should produce:
#
# ```ruby
# 5.stringify(10) #=> "5"
# 5.stringify(2)  #=> "101"
# 5.stringify(16) #=> "5"
#
# 234.stringify(10) #=> "234"
# 234.stringify(2)  #=> "11101010"
# 234.stringify(16) #=> "EA"
# ```
#
# Here's a more concrete example of how your method might arrive at the
# conversions above:
#
# ```ruby
# 234.stringify(10) #=> "234"
# (234 / 1)   % 10  #=> 4
# (234 / 10)  % 10  #=> 3
# (234 / 100) % 10  #=> 2
#                       ^
#
# 234.stringify(2) #=> "11101010"
# (234 / 1)   % 2  #=> 0
# (234 / 2)   % 2  #=> 1
# (234 / 4)   % 2  #=> 0
# (234 / 8)   % 2  #=> 1
# (234 / 16)  % 2  #=> 0
# (234 / 32)  % 2  #=> 1
# (234 / 64)  % 2  #=> 1
# (234 / 128) % 2  #=> 1
#                      ^
# ```
#
# The general idea is to each time divide by a greater power of `base`
# and then mod the result by `base` to get the next digit. Continue until
# `num / (base ** pow) == 0`.
#
# You'll get each digit as a number; you need to turn it into a
# character. Make a `Hash` where the keys are digit numbers (up to and
# including 15) and the values are the characters to use (up to and
# including `F`).

I’d like to change the letters to be lowercase instead of uppercase as that is what the tests test for.