my $input;
unless ( $input = shift )
{
    # read from DATA
    my @tunes = grep { $_ !~ /^#/ and /\S/ } <DATA>;
    chomp($input = $tunes[rand(@tunes)]);
}
[download]

__DATA__
# Original: 
<75>[1]vV+|:{1(1)/1C/DEFG+ABCDEFG+ABCBAAbADCBAA-GF#GrG+E-GrF+E-FrF+D-F
+rE+D-ErE+C-ErD+C-DrD+B-D^+Cr}:||:(.25)2G+CEDCBA-GFEDCBA-GF*E+EFF#G.E`
+Dr:|=1vV-|:{2(2)1C/E~CF~CE+CAB-G#+A-FGCr}:||:(2)EDCB:|=2vV-|:{3(2)0C/
+ECFCE+CAB-G#+A-FGCr}:||:(2)GGGG:|=3

# Twinkle Twinkle Little Star (Main Theme)
vV+[1]|:{aCCGG+AA-GGFFEED/D.E`^C/}:|GGFFEEDDGGFFE/E.F`*E~D=avV-[-1]|:{
+bC+CECFCECDBCA-FG*C/}:|+E-G+D-G+C-G+B-G+E-G+D-G+C/C.D`@n*C~B-=bvV-[-1
+]&n*G

# TTLS Variation 1
vV+[1]_|:{aDCBCBCBC+A-GF#GF#GF#GG#+ACBDCBAA~-G+EDCBA-GG~F+DCBA-GFF~E+C
+BA-GFE*D+A~-GB*Cr_}:|+A-GF#GF#G+A-GGFEFEFGFFED#ED#EFEEDC#DC#DED+A-GF#
+G+ECA-GGFEF+DB-GFFED#E+C-GFE*G.~E`*D_=avV-[-1]{bC~+C~E~C~F~C@nE/r.C#`
+*D/r.B`*C/r.A`*-FG/}+C-GEG*=b*+C-C+E~-G~+D~-G+C~-G~+F~-G*@o+ED/C/r.C`
+E.C`*B[-2]=b*+C-CvV-[0]&nC&o*-GG/GrG

# TTLS Variation 2
vV+[1]|:CCGG@nGFFEEDDCCB-Gr+:||:|:GG~FF/E.D`E.F`*E~D:|C~/CB`C`*GG~+AA~
+-GG~F#F~EE~DDCr:|vV-[1]|:*R+A-G/FFEEDDCr:||:CC~CB/C.D`E.F`^B/CC~CB/-G
+.+D`E.F`^-G/Grr+C~CC~CBbAAb-G+A~A/-G.F`*Er+:|vV-[-1]|:_C+CBCDCBC-E+CB
+CDCBC-F+CBCDCBC-C+CBCDCBC-A+AAbA-B+BBbB-C+CBC-A+AAbA--F+FEF-G+GF#G^-C
++C:||:_G+EEbEFEEbE-G+DDbDEDDbD-G+GF#G+A-GF#G-G+FEFGFEF-G+EEbEFEEbE-G+
+DC#DEDC#D-G+CBCDCBC-G+BBbBCBBbB-C+CBCDCBC-E+CBCDCBC-F+CBCDCBC-C+CBC-C
+#+C#BC#-D+DC#D-B+BBbB-C+CBC-A+AAbA--F+FEF-G+GF#G^-C+C:|

# TTLS Variation 5
vV+!40!+|:C/rC*G/rG*+A/rA-*G/rGrFrFrErErDrD*Cr:||:G/rG~*F#/rF~*E/rEb~*
+D/r-G+*G/r/G~F#~^F/r/F~E~^Eb/r/F#~G~^D/r/F~D~^C/r/C~E~^G/r/G~E~+^A/r/
+A~C~^-G/r/E~GRG~F#RD~FRF~ERG~ERC#~DRF~DRB~C^r:|vV-!40!+|:RRRr/rErErDr
+DrCrCrB*Cr:|vV-!40!|:/rCERECRFCRECrDrBrCrA-rFrGR+C-*C+:||:|:/rE-*G/r+
+D-*G/r+C-*G/r+B-*G+:|-/r/C~E~^G/r/+C~E~^G/r/F~+A~-^C/r/E~G~^C/DrBrCr-
+ErFrGr+Cr-Cr+*:|
[download]

Even better, add some "computer generated music" functionality, to get something harmonious and interesting, yet different every time.