'Constructor
@todo: do not use lists or dicts as parameter defaults!
@todo: parameter description'

def __init__(self, range=[(-1), (-0.5), 0, 0.5, 1], colour={(-1): '#888888', 0: '#000080', 1: '#008000', 2: '#FFFF00', 3: '#FFA500', 4: '#FF0000', 5: '#880088'}, opacity={(-1): 0.5, 0: 0.6, 1: 0.6, 2: 0.7, 3: 0.7, 4: 0.8, 5: 0.8}, image={(-1): 'grey', 0: 'blue', 1: 'green', 2: 'yellow', 3: 'orange', 4: 'red', 5: 'purple'}, desc={(-1): 'No    Data', 0: 'Very    Low', 1: 'Low', 2: 'Medium    Low', 3: 'Medium    High', 4: 'High', 5: 'Very    High'}, zero=True):

    self.range = range
    self.colour = colour
    self.opacity = opacity
    self.image = image
    self.description = desc
