docs: def find_snapshots(network, carrier, maximum = True, minimum = True, n = 3):
      
      """
      Function that returns snapshots with maximum and/or minimum feed-in of 
      selected carrier.
  
      Parameters
      ----------
      network : :class:`pypsa.Network
          Overall container of PyPSA
      carrier: str
          Selected carrier of generators
      maximum: bool
          Choose if timestep of maximal feed-in is returned.
      minimum: bool
          Choose if timestep of minimal feed-in is returned.
      n: int
          Number of maximal/minimal snapshots
  
      Returns
      -------
      calc_snapshots : 'pandas.core.indexes.datetimes.DatetimeIndex'
          List containing snapshots
      """
      
      if carrier == 'residual load':
          power_plants = network.generators[network.generators.carrier.
                                      isin(['solar', 'wind', 'wind_onshore'])]
          power_plants_t = network.generators.p_nom[power_plants.index] * \
                          network.generators_t.p_max_pu[power_plants.index]
          load = network.loads_t.p_set.sum(axis=1)
          all_renew = power_plants_t.sum(axis=1)
          all_carrier = load - all_renew
  
      if carrier in ('solar', 'wind', 'wind_onshore', 
                     'wind_offshore', 'run_of_river'):
          power_plants = network.generators[network.generators.carrier
                                            == carrier]
  
          power_plants_t = network.generators.p_nom[power_plants.index] * \
                          network.generators_t.p_max_pu[power_plants.index]
          all_carrier = power_plants_t.sum(axis=1)
  
      if maximum and not minimum:
         times = all_carrier.sort_values().head(n=n)
  
      if minimum and not maximum:
         times = all_carrier.sort_values().tail(n=n)
  
      if maximum and minimum:
          times = all_carrier.sort_values().head(n=n)
          times = times.append(all_carrier.sort_values().tail(n=n))
  
      calc_snapshots = all_carrier.index[all_carrier.index.isin(times.index)]
  
      return calc_snapshots