Transpose MIDI files into C Major or A Minor

transposer.py

#converts all midi files in the current folder

import glob
import os
import music21

#converting everything into the key of C major or A minor

# major conversions
majors = dict([("A-", 4),("A", 3),("B-", 2),("B", 1),("C", 0),("D-", -1),("D", -2),("E-", -3),("E", -4),("F", -5),("G-", 6),("G", 5)])
minors = dict([("A-", 1),("A", 0),("B-", -1),("B", -2),("C", -3),("D-", -4),("D", -5),("E-", 6),("E", 5),("F", 4),("G-", 3),("G", 2)])


#os.chdir("./")
for file in glob.glob("*.mid"):
    score = music21.converter.parse(file)
    key = score.analyze('key')
#    print key.tonic.name, key.mode
    if key.mode == "major":
        halfSteps = majors[key.tonic.name]
        
    elif key.mode == "minor":
        halfSteps = minors[key.tonic.name]
    
    newscore = score.transpose(halfSteps)
    key = newscore.analyze('key')
    print key.tonic.name, key.mode
    newFileName = "C_" + file
    newscore.write('midi',newFileName)
            
    

I feel very silly, this is my first time ever using python. I'm trying to transpose a midi file to C but I'm unsure as to how! I've installed python and typed the location of this .py file, and even dragged and dropped. It states "SyntaxError: unexpected character after line continuation character"

File is in a folder on desktop with the Midi file wanting to be changed.

hi! Thankls for the great work.... i feel the info on midi channels got changed through running this script?