List valid parameter combinations based on user specified parameters

[redfrexx]

This could look like this, but it would then require adding a calculate() method to the example above to enable multiple functions to be called for a specific transport mode.

from co2calculator import Trip, BusCarFuel, Size

# Calculate co2 emission using 'calculate()'
Trip(distance=300).by_car(fuel_type=BusCarFuel.DIESEL).calculate()

# Get valid parameter options based on user chosen parameters
trip = Trip(start='Heidelberg', end='Freiburg')
# print options as dictionary
trip.by_car(fuel_type=BusCarFuel.DIESEL).get_options()
# Returns {'size': [Size.SMALL, Size.LARGE]}