Which Key is this written in?

Which Key?

#Bsong1.rb
# 12 Oct 2017
# Use circle of fifths to cycle through
# all major keys using the property that
# chords 1,4 and 5 are major chords in that key
# and key modulation works well with an adjacent
# key on the circle of fifths
##############
#helper function
def midi2note(n)
  nn=note(n)
  if nn==nil
    return nn
  else
    nn= note_info(nn)
    nnn=nn.to_s.split(":")
    mmm= nnn[3].chop
    return mmm
  end
end # midi2note
######
#Define tempo and note lengths and release fraction
#####
tempo=2.0
#define note timings
whole=1.0
half=whole/2.0
dothalf=half*1.5
quart=half/2.0
dotquart=quart*1.5
eighth=quart/2.0
doteighth=eighth*1.5
sixteenth=eighth/2
###################
#define some midi intervals
octave=note(:C5)-note(:C4)
fourth=note(:f4)-note(:c4)
fifth=note(:g4)-note(:c4)
third=note(:e4)-note(:c4)
one= note(:d4)-note(:c4)
#####
use_synth :fm
with_fx :level, amp: 0.3 do
  x=note(:c4)
  puts x
  j=x
  #  y=chord(j,:major)
  y=[j,j+third,j+fifth]
  k=[]
  i=0
  while i<3
    puts midi2note(y[i])
    play y[i]
    sleep quart
    i+=1
  end
  while j!=72
    j+=fourth
    if j>(x+octave)then j=j-octave end
    #    y=chord(j,:major)
    y=[j,j+third,j+fifth]
    i=0
    while i<3
      puts midi2note(y[i])
      play y[i]
      sleep quart
      i+=1
    end
    j+=one
    if j>(x+octave)then j=j-octave end
    #    y=chord(j,:major)
    y=[j,j+third,j+fifth]
    i=0
    while i<3
      puts midi2note(y[i])
      play y[i]
      sleep quart
      i+=1
    end
    k=k.push(midi2note(j))
  end
  puts k
end

["G4", "D4", "A4", "E4", "B4", "Fs4", "Cs4", "Ab4", "Eb4", "Bb4", "F4", "C5"]