docs: def verlet(dfun, xzero, vzero, timerange, timestep):
      '''Verlet method integration. This function wraps the Verlet class.
  
          :param dfun:
              second derivative function of the system.
              The differential system arranged as a series of second-order
              equations: \ddot{X} = dfun(t, x)
          :param xzero:
              the initial condition of the system
          :param vzero:
              the initial condition of first derivative of the system
          :param timerange:
              the start and end times as (starttime, endtime)
          :param timestep:
              the timestep
          :returns: t, x, v:
              as lists.
      '''
      return zip(*list(Verlet(dfun, xzero, vzero, timerange, timestep)))