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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 get_solarposition(time, latitude, longitude, altitude=None, pressure=None, method='nrel_numpy', temperature=12, **kwargs):
 """ A convenience wrapper for the solar position calculators. Parameters time : pandas.DatetimeIndex latitude : float longitude : float altitude : None or float, default None If None, computed from pressure. Assumed to be 0 m if pressure is also None. pressure : None or float, default None If None, computed from altitude. Assumed to be 101325 Pa if altitude is also None. method : string, default 'nrel_numpy' 'nrel_numpy' uses an implementation of the NREL SPA algorithm described in [1] (default, recommended):
 :py:func:`spa_python` 'nrel_numba' uses an implementation of the NREL SPA algorithm described in [1], but also compiles the code first: :py:func:`spa_python` 'pyephem' uses the PyEphem package: :py:func:`pyephem` 'ephemeris' uses the pvlib ephemeris code: :py:func:`ephemeris` 'nrel_c' uses the NREL SPA C code [3]: :py:func:`spa_c` temperature : float, default 12 Degrees C. Other keywords are passed to the underlying solar position function. References [1] I. Reda and A. Andreas, Solar position algorithm for solar radiation applications. Solar Energy, vol. 76, no. 5, pp. 577-589, 2004. [2] I. Reda and A. Andreas, Corrigendum to Solar position algorithm for solar radiation applications. Solar Energy, vol. 81, no. 6, p. 838, 2007. [3] NREL SPA code: http://rredc.nrel.gov/solar/codesandalgorithms/spa/ """


    if altitude is None and pressure is None:
        altitude = 0.
        pressure = 101325.
    elif altitude is None:
        altitude = atmosphere.pres2alt(pressure)
    elif pressure is None:
        pressure = atmosphere.alt2pres(altitude)

    method = method.lower()
    if isinstance(time, dt.datetime):
        time = pd.DatetimeIndex([time, ])

    if method == 'nrel_c':
        ephem_df = spa_c(time, latitude, longitude, pressure, temperature,
                         **kwargs)
    elif method == 'nrel_numba':
        ephem_df = spa_python(time, latitude, longitude, altitude,
                              pressure, temperature,
                              how='numba', **kwargs)
    elif method == 'nrel_numpy':
        ephem_df = spa_python(time, latitude, longitude, altitude,
                              pressure, temperature,
                              how='numpy', **kwargs)
    elif method == 'pyephem':
        ephem_df = pyephem(time, latitude, longitude,
                           altitude=altitude,
                           pressure=pressure,
                           temperature=temperature, **kwargs)
    elif method == 'ephemeris':
        ephem_df = ephemeris(time, latitude, longitude, pressure, temperature,
                             **kwargs)
    else:
        raise ValueError('Invalid solar position method')

    return ephem_df