from datetime import datetime


def get_highest_volume(volume_history):
    """Returns the date with highest trading volume.
    
    Return is format: [highest volume, date with highest volume].
    """
    highest_volume = 0
    highest_volume_timestamp = 0
    for timestamp in volume_history:
        if(volume_history[timestamp] > highest_volume):
            highest_volume = volume_history[timestamp]
            highest_volume_timestamp = timestamp
    return([highest_volume, 
            datetime.fromtimestamp(highest_volume_timestamp / 1000)])