Note translator, Engish to lilypond

gistfile1.py

def parseNote(note):

    """translates English notes to (default) lilypond notes"""
    
    """takes a string consisting of a note name 'a', 'b', 'c', 'd', 'f', or 'g'
    (note names can be either upper or lower case)
    optionally followed by a '#' or 'b' to signify sharps and flats, followed by
    an octave number corresponding to the note's piano octave.
    returns a default lilypond representation of the note in absolute octave
    notation.  Spaces are ignored.  returns None if the input is invalid."""
    
    try:
        
        note = note.replace(' ', '')
        
        piano_octave = eval(''.join([ i for i in note if i.isdigit() ]))
        ly_octave = piano_octave - 3
        if ly_octave > 0:
            octave_marker = "'" * ly_octave
        elif ly_octave < 0:
            octave_marker = ',' * ly_octave
        else:
            octave_marker = ''
    
        note_name = note[:(-1 * len(str(piano_octave)))]
        if len(note_name) > 2:
            raise KeyError
        if note_name[0].lower() not in 'abcdefg':
            raise KeyError
        if len(note_name) == 2:
            if note_name[1] == 'b':
                accidental = 'es'
            elif note_name[1] == '#':
                accidental = 'is'
            else:
                raise KeyError
        if len(note_name) == 1:
            accidental = ''        
        note_letter = note_name.lower()[0]

    except Exception:
        print '\nnot a valid note input'
        return None
    return ''.join([note_letter, accidental, octave_marker])