Energy
    string = double .. [kKMGT] .. [W|J] ([]=regex char matches)
    k = 1000
    M = 1000000
    G = 1000000000
    T = 1000000000000
    
note 'W' divides amt by 60
    
errors:
    nil
        throws error("Empty energy value.")
    size-1 != 'W' or 'J'
        throws error("Energy amount has to be specified in W or J (Watts or Joules)"
    size < 2
        throws error("Energy value missing")
