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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def from_vaspruns(cls, vaspruns, specie, initial_disp=None, initial_structure=None, **kwargs):
 """ Convenient constructor that takes in a list of Vasprun objects to perform diffusion analysis. Args: vaspruns ([Vasprun]):
 List of Vaspruns (must be ordered in sequence of MD simulation). E.g., you may have performed sequential VASP runs to obtain sufficient statistics. specie (Element/Specie):
 Specie to calculate diffusivity for as a String. E.g., "Li". initial_disp (np.ndarray):
 Sometimes, you need to iteratively compute estimates of the diffusivity. This supplies an initial displacement that will be added on to the initial displacements. Note that this makes sense only when smoothed=False. initial_structure (Structure):
 Like initial_disp, this is used for iterative computations of estimates of the diffusivity. You typically need to supply both variables. This stipulates the initial stricture from which the current set of displacements are computed. \\*\\*kwargs: kwargs supported by the :class:`DiffusionAnalyzer`_. Examples include smoothed, min_obs, avg_nsteps. """


        def get_structures(vaspruns):
            for i, vr in enumerate(vaspruns):
                if i == 0:
                    step_skip = vr.ionic_step_skip or 1
                    final_structure = vr.initial_structure
                    temperature = vr.parameters['TEEND']
                    time_step = vr.parameters['POTIM']
                    yield step_skip, temperature, time_step
                # check that the runs are continuous
                fdist = pbc_diff(vr.initial_structure.frac_coords,
                                 final_structure.frac_coords)
                if np.any(fdist > 0.001):
                    raise ValueError('initial and final structures do not '
                                     'match.')
                final_structure = vr.final_structure

                assert (vr.ionic_step_skip or 1) == step_skip
                for s in vr.ionic_steps:
                    yield s['structure']

        s = get_structures(vaspruns)
        step_skip, temperature, time_step = next(s)

        return cls.from_structures(
            structures=list(s), specie=specie, temperature=temperature,
            time_step=time_step, step_skip=step_skip,
            initial_disp=initial_disp, initial_structure=initial_structure,
            **kwargs)