Given a list of notes in a song (pitch letter C D E F G A B plus octave 0-7, e.g. C5), the lowest note and the highest note the singer can sing, write a function singable(song, low, high) that returns whether every note in the song is within the singer's range.
Asked in the phone screen stage. Notes are ordered by octave first, then pitch letter. Complexity should be expressed in terms of N = length of the song.
song is a list of note strings, and low and high are note strings. Return True if every song note is between low and high, inclusive; otherwise return False.
def singable(song, low, high):