Complete a function that calculates the average tempo (in beats per minute, BPM) of tracks for each musical key. Each track is represented as a dictionary containing various fields, including tempo and key.

Inputs:

• tracks: A list of dictionaries, where each dictionary represents a track and contains at least the following fields:
  • tempo: A float representing the tempo of the track in BPM.
  • key: An integer representing the musical key of the track, ranging from 0 to 11.

Steps:

• Iterate Through Keys:

  • Loop through each musical key from 0 to 11.
  • For each key, create a list key_tempos that contains the tempo of tracks with the current key.

• Calculate Average Tempo:

  • If key_tempos is not empty, calculate the average tempo by summing the tempos and dividing by the number of tempos.
  • Store the calculated average tempo in average_tempos with the current key as the dictionary key.